IMO and experience, the best do-it-at-home exercises for drummers are:
1. Push ups. It really releases the tension in your arm and it will save you from cramps.
2. Squats. For endurance.
I do this if I don't have time to go to the gym.
My band, we used to play 4 hours per gig. Don't ask me why, it's not required of us..but when you play rock and roll, and the blues, the feeling and emotion just won't let you stop playing 45mins to an hour per set. And you bet it, because its rock and roll, most of "our" fearless band leader would never require dynamics, its all power. I'd burn my leather Zildjian gloves in 2 months of playing. Magastos din ako sa sticks that's why from Pro Marks, I had to switch to Lazers beefy 5Bs.
So that's how important exercising is.