Fitness training is simply a system of checks and balances. Just like the rest of your life. If you put in a hard workout, you need to replenish your system with good, wholesome food. You did a whole days worth of work after your workout? This may require up to 9-10 hrs of sleep to let your body properly recover. If you lift weights often and stress your muscles, make sure you’re taking care of them by getting massages (or self massage with a foam roller), stretching often, and warming up and cooling down properly. For me, this also involves my weekly visit to my chiropractor. It’s important for my spine and joints to be aligned properly before I throw a bunch of weight on it week after week. Life knocks us out of alignment with routine events, so make sure you’re back on track before you expect your body to deliver for you!
bhinesinmotion.com 
I think this is one of the most underrated parts of fitness. I compete in powerlifting and as a general rule, they’re not receptive to the idea of stretching or cooling down. Warming up is okay as long as it involves a barbell.
My viewpoint is my training today is to make my life better in twenty years, it’s an investment in the future me so I need to address all of my future needs not just the ones that feed my ego today.
Good post.
Thanks for the great comments John! You have excellent points, I couldn’t agree more.