I'm fortunate that my job gives me the motivation to be as fit as possible. I wound up in a profession that requires physical and mental preparation, so I get to prepare like an athlete for everything I do. I'm living the dream, man.
Unless you do your best, the day will come when, tired and hungry, you will halt just short of the goal you were ordered to reach, and by halting you will make useless the efforts and deaths of thousands.
The two things I did learn were that you are as powerful and strong as you allow yourself to be, and that the most difficult part of any endeavor is taking the first step, making the first decision.