I'm 42 so I understand what your saying.....
Guys - Guys!!!! You are both still very young! I'm 57, not in the greatest shape (need to lose 20 pounds), but consider myself healthy as a horse (despite a heart attack with fibrillation at the age of 47).
If 57-year old women with a shaky ticker were allowed to enlist in the military, I'd be there tomorrow. The only way I've been able to contribute is with money (can't even donate blood since 1991).