It's not the workout you're excited about that counts. The workout you feel great going into and better coming out of that matters. It's not the workout you have energy for that makes a difference. It's not the workout you carefully took the time to plan down to the second that makes you stronger.
No.
It's the workout you did after a long day at work. The workout you did despite feeling mentally drained. Physically exhausted. The one you dread, but do anyway because you don't accept excuses. The one you took your expensive pre-workout supplement before hand just so you would not talk yourself out of it on your way to the gym. The one that continued to the end only because you kept repeating in your head "there are either excuses or results, but never both".
The ones you drag yourself to the locker room, drenched in sweat, and it takes all the strength you have left to lift your gym bag, and the remaining mental capacity just to drive home. Those are the workouts that make you different from the rest of the athletes on the field. That make you a champion.
True, any kind of activity will improve physical fitness, but only the ones that were just as hard to finish as they were to start improve your mental fortitude.
