How much time will I have for college and fitness as an active duty 91b in the army?

It'd help to know more specifics...what major do you want? What ambitions do you have? Senior enlisted? Warrant? Commissioned? Did you want to stay in, or eventually get out? From long and often aggravating experience, here are the rules, at least when I was in, and after I'd gotten out, OK? It's really hard to do coursework, quite often, in something other than what you're expressly working in; that's just a truism I'd observed all the time I was in. Now, that being said, full time for undergrad is 12 credits to start in a given semester, or quarter, as the case my be, full time for grad is 9 credits, due to increased difficulty, and a fundamental recognition that in grad programs, people generally work. If you are getting Federal loans, which, of course, differs completely from active duty funding, you need to have at least 6 credits going at the end of a semester, if you drop any coursework, which you need to find out the explicit rules and dates for, both for getting drop forms signed, as well as giving drop forms in, to a registrar office. Also, you need to get the actual catalog for whatever school you're going to, actually print it out if it's an online PDF, as the case may be, and actually go through it. While what I'm about to say isn't a necessarily hard and fast rule, the catalog in effect when you start a program, is, for all practical intents and purposes, at least from the user end, I'd found, essentially the agreement between you and the school, as to the rules in place, applicable to you, at the time you actually start, that applies to how long you have to finish, all regionally-accredited degree programs, by law and/or policy, I believe, actually have set time limits, however long that might be, expressly listed in a catalog, at least, that was the case for me in all the programs I'd been in; it could be five years, or whatever, the point is, the undergrad and/or grad catalogs of any school you go to are, typically, required to actually list such info concretely (that's, in fact, how I was actually able to finally finish my clinical allied-health doctorate before my total perm disability, long, long story, not germane here). If you get TA to pay the tuition on active, trust me, you MUST, MUST, MUST get your grade slip in, by a definite date after finishing, or you're gonna either be hounded by your installation educ ofc, or have to wind up paying it back; that happened to me a couple of times with coursework I did under a program before you were in called VEAP, which existed before the present GI bill, where I put in $2700, the VA put in an addl $5400, max, for $8100 in all, that's all I was allowed, I eventually took the rest of the $2700 out, probably dumb back then, though that's what I'd done, it was a long while ago, obv. It'd also help to know grades, GPAs, actual course titles you've done thus far and/or want to do; further, if your installation has colleges in to do coursework where you are, physical convenience is a REALLY good thing to try to take advantage of, when you're doing coursework on active. I learned a long, long time ago, another truism: Generally, one can work and drive, drive and go to school, or go to school and work, however, short of being Superman with a big red "S" on your chest, and a cape, few normal humans can work, drive, and go to school, all at once. Something's gotta give; you're just gonna wind up burning the candle at both ends, and wind up crashing and burning, God knows, it happened to me more than once. I did m first masters part time, it took me five years, and was a MAJOR pain, I made it WAY harder than it needed to be, going WAY further than I'd needed to, I could've gone to a masters in physics as opposed to engineering WAY closer to where I'd been working initially after I'd gotten out, in short, I had pretty much zero clue how to go about the whole thing properly. That being said, take some advice from one who's been around just about every educ block for which God has streets, and give us all WAY more info on you. About the weightlifting, the more you distract yourself, the less you're gonna be able to concentrate on coursework; I entirely fathom why you'd wanna do such stuff, you need to for your APFT, or whatever PT requirements you'd be subject to, I also get that, running included...that being said, the more you relate here, the more all of us can try to help you with such career/educ stuff, so, if you wanna chat more, just lemme know, I'll try to suggest what I can, no rush, whenever you want...if you want a STEM field, be specific about why, what you've taken thus far, etc...if a non-STEM field, the same...paramount, give us your explicit objectives, EXACTLY what you're trying to accomplish, what you eventually wanna do and/or be, after such training...college isn't a voc-ed program, that's not its purpose, and never was, its purpose is to develop the intellect...it's also not supposed to be torture, as well, however, the fewer physical distractions you have while doing it, the easier and less aggravating it obv tends to be, honest, trust me, been there, done that (BTDT), many, many times over, I assure you, OK?

College is really not that hard. TA only pays for a couple of classes a year so you'll only be taking one or two at a time. In your lower level classes you'll probably spend 1-2 hours per week per class.
You'll have PT every morning and plenty of time to work out

I figure all that oughta keep you going for a fair while...if you want more, just lemme know, as I'd said, no rush, whenever you'd want, OK?