I have been in better than average shape my entire life, this year I started a program that has me in better shape than I thought I could achive at my age 52.
Crossfit claims it will prepare you for anything, and I say they have in my case.
It's used by a lot of military and police officers. The best part of the whole program is it doesn't cost anything. They give you a workout to do on their website free daily. You can do most exercises at your local gym, or in your garage with a home gym.
Now be warned this is the most intense fitness program I have ever attempted, but I have stayed with it for ten months and I am in extremely good shape. I have found that it makes easier what all hunters do in the field. Like they say it prepares you for anything. Also when you look at the daily workouts just remember everything can be scaled to your personal ability level. So if anyone is interested checkout crossfit.com and good luck