I have never gotten an endorphin rush from exercise of any sort. I've never gotten an endorphin rush from solving a programming problem or any problem. Helping people feels good. Making sure people are organized feels good.

Edit: I always find it incredibly strange when people describe exactly like in this article "feeling like a fucking god" after doing something. Like, you ok? Having a manic episode? That seems like an overstatement and maybe you shouldn't be making any life decisions after doing something because feeling that good shouldn't be a reasonable frame of mind for decision making.