What was it like to go from office worker to essentially Infantry by reclassifying to combat arms/12B?

Don't be the "essentially" guy. Infantry is infantry. Comm is Comm. etc is etc.

If you like the job do the job. If you want a new job then switch. I started out Infantry and eventually moved to Comm. There is a process to transfer because it happens pretty often. Just be committed to the job. All eyes will be on you and people will expect you to be a sponge to absorb everything.

Also to add to this I’ve heard there is some math associated with this MOS. Could somebody please give me an example of it?

Apologies for the double post. But to answer your second question, no. There are 0 civilian jobs you will get from the 12B skill-set alone. Can personally confirm this as I ran into this issue when transitioning from Regular Army to Guard.

Also, common misconception about 12B is “math intensive.” There’s nothing difficult about Engineer math. If you can do simple addition (1.25 + 1.25 = 2.5) and the OCCASIONAL simple multiplication, that’s about as hard as it gets. Sapper School and 18C I imagine it gets a bit more math heavy, but definitely not as a regular enlisted Engineer.

I enlisted as a 12B and was at Fort Hood my first enlistment. Now I’m a 92Y AGR. I love the Engineers and a lot of my friends are 12B, but without any hesitation I can tell you I’m not going back to 12B. Like any MOS, your experience can vary widely depending on what unit you go to, but to me, 12B training and METL tasks felt archaic and about half a century outdated.

Talk with a 68W that's had CBT Arms and Hospital assignments... or maybe a fellow 92Y that's been assigned to a CBT Arms BN... If you're going to reclass go for something that that works in the civilian world like MP, Aviation, Wrench turner(Mechanic), although, logistic MOS could get you employed as a dispatcher by:
SWIFT, CONSOLIDATED FREIGHT, WARNER, SCHNEIDER TRUCKING....

What it boils down to is "paperwork" will be required regardless of which MOS you decide to reclass to

I feel uniquely qualified to answer this question.

I joined the Navy at 17, I did it to get out of bad home situation. The only person who gave me any advice when joining about job selection was to tell me "go into electronics it is something you can use on the outside". I joined the Navy undesignated. An undesignated sailor is given one of three apprenticeships (4 weeks of school), either aviation, firemen, or seaman. As an aviation sailor you, generally, end up in the AB rate. as a Seaman you, generally, end up as a boatswains mate, and I am not sure where the firemen end up. The idea is that you get the bare minimum training so you don't fall off the side of the ship, and then you get sent to fleet. While there you are allowed to explore all the jobs the Navy has and pick one you like. You do the 3&2 manual for said rate and you become known as a "striker" and if you pass and advance the ratings exam, and make 3rd class, you become that rate. After about a year in the fleet, you can request an A school, some rates require you to be school trained.

So I joined the Navy and about 3 days later I was in Boot camp, never had a chance to even regret the decision before I was pushed into the reality of what I had done. Boot camp was hard for me, I was not prepared for military life, as I had major authority issues. It comes from raising yourself, while your mother is in a bottle. About the fourth week of boot camp another recruit said, "I can't wait till we get to our first ship." I responded, "What do you mean ship." and he said, "What the fuck did you think you were going to do Ison, you joined the Navy." So, now I am in a panic, wondering what the fuck ship life is going to be like. In the 5th week of boot camp we went into classification where they verified our rate choice and worked out any last kinks before you were shipped to A school. At this point you have the option of picking a rate, if you are undesignated. My company commander said, "All of you dumb asses that signed up undesignated better pick a rate, you don't want to go to the fleet undesignated." So, I am in super panic mode now, so i do the dumbest thing I could have ever done, I choose a rate in electronics, because other people told me it was good for me.

So they send me to A school for aviation Electronics technician, 3rd hardest school in the Navy next to ET Nuke and strait ET. A school fucking sucked 9 more months in a training command run like boot camp. I hated my rate, I hated the people in my rate, I hated the work, it just fucking sucked. My first command was an A-7 squadron and i spent my first year in the fleet in the line division, as a Plane Captain, I loved it, it was the best time I had in the Navy, and had I known what I know now I would have stayed undesignated and struck for AB(H) (Yellow Shirt).

The base where we were stationed had 'special weapons' onsite. Each squadron had people from it who were assigned as "auxiliary security forces". Our job was to train with the Marine Security forces on post, and to augment them in base security, mostly the special weapons depot. This was my first chance at being a fleet marine force sailor. After my unit was decommissioned, I made a really dumb ass mistake and went I level in Diego Garcia, as I wanted to avoid sea duty. While in Dodge I did an out of path advancement to 3rd class as an HM. I wanted to go green side, but you have to be school trained for this, you need the 8 week MCB course where they teach you to be a field medic. I did not have this, but they shipped out of Dodge to Okinawa where I was assigned to the Marine Air Group. I was sent to the Tarawa and supported the Marines in Somalia, as a fleet marine force sailor. This was when i realized I should have joined the Army. I wanted to be in the infantry, i just did not want to be a Marine.

I got out of the Navy and went into the Army. My navy Rate of AT, what I was trained as, was the MOS they converted. I was able to choose 33T, CEWI Technician. This job in the Army sucked just as much as the AT rate did in the Navy. So when I enlistment was up, I got out and joined the National Guard, as an 11B. I spent three years in an infantry unit and loved every minute of it. I left the guard because of my daughter, but I joined back up after 9/11. This time I chose an armored unit because I was starting to get old, and the idea of walking everywhere with 60 pounds of shit was not all that appealing. I deployed with this unit to Iraq, as a 19D.

I wanted to be a soldier. I joined the Navy because it got me out of the home, but if I had it to do over again I would have gone strait army and strait into the infantry.

I knew a guy one time who was a signal MOS. He said, "I like being Signal 'cause I get to do all the shit an infantry guy does, plus signal shit." I responded, "I like being infantry cause I don't have to put up with signal nerds."

There was a Marine Corps Corporal in my A school. He was form the infantry he told me he was retraining because "He hated the people in his unit so much he spent most of his time in the motor pool."

If you don't like being a clerk then definitely change your MOS. As a SGT yoau re going to be expected to be a "subject matter expert" and you can't do that in as a 12B there is too much shit you would have needed to learn as a specialist, same thing for just about any other combat arms position except infantry. You can learn all you need to know as a SGT in the infantry in the first few months. There are other MOS that you can look into; MP, for instance, would get you out of the office too.

If you can't handle paperwork, you ought not reenlist. This entire industry is the wrong career for anyone with that feeling. The same is true for those who can't handle "customer service".

Isn't the proper term "Infantry with a degree"?

I was 11a,11b moving to 12b.... As a combat engineer, you will use your intellect and hopefully be more productive if you can keep from killing all of your buddies by rushing through requirements and making improper decisions while performing your duties... Granted those issues also accompany i Infantry

You need to do some serious soul searching.