I watch people train all day. They lift, they jog, they stretch, and sometimes they come back again. Most do not, but those that do usually see results. But then there are those that I see every day and seem to be treading water. They bang away at the equipment in desperation and frustration, hoping to see any benefit from their pain. Experience has taught us many ways to improve the human body that science has backed up. And while there are many roads to Rome, some just get you there faster. The fastest way to results is also the easiest to remember: Consistency, Progression, and Recovery.
If you want to improve a movement, you should do it often. If you want to run faster, run more. If you want to do more pull-ups, do more pull-ups. Most of the time it really is that simple. If your goals are more general than that ("I just wanna look good naked!"), then a good place to start is 5 hours a week of sweaty-time fun. 2-3 sessions of resistance training and 2-3 sessions of cardio. If your goals are more specific ("I wanna squat 5000lbs!") then you should program with that goal in mind, but do something that gets you closer to it every day.
Progress the Load
One of the biggest mistakes that I see consistent people make is being too damn consistent. I have clients that tell me, "I've run 5 miles a day since high school, and I'm still gaining weight!" Well unfortunately, your body adjusts to whatever load you give it. If you want to improve your performance, or even maintain them, you are going to have to up the ante. If you run every day, try and run faster. If you do 100 push-ups a day, try working up to 1-arm push-ups. You should not think that you have to go as hard as you can every day, but you need to be progressively overloading your body on a fairly consistent basis.
Recover and Repeat
Recovery means stretching and refeeding your muscles and sleeping. Your muscles need to be worked and stretched to maintain your mobility. They need to be fed (with protein and carbs) in order to work at full capacity again. And you need to sleep to get all this biochemistry done. Sleep is vital for muscle turnover and hormone repletion (which you need to lose fat). And worse of all, if you get less than 6 hours a sleep a night, you are likely not improving your body at all. You are probably increasing the levels of cortisol in your system to levels that will do it long term harm. So stretch right after you run or lift, eat well in the 3 hours after you work out, and go to frickin' bed already!