For career military, what was your length of service

For those who have made a career out of the military, active or retired, what is your planned length of service or how many years did you do before retirement? If you didn't stay until 35 years or more, do you wish you had or glad you left and moved on?

I served my 4 years and got out, retired from the FAA as an Air Traffic Controller after 29 years, but if I had stayed in, then next Aug would be 40 years. There have been times I have missed the military and think I should of stayed in, that was my original goal at the time. I guess we all miss stuff from our past. Just started thinking of this because my oldest great nephew has decided he wants to make the Army a career, started college on an ROTC & football scholarship. Even went to West Point at the request of the football coach (long snapper), but didn't get to go.

So just an older guy looking back on life and thinking what if.