It's not really that surprising. Why would a living thing want to exert itself for no real reward? I think biologically we want to conserve as much energy as possible.

It's only with modern medicine that we can analyze cause/effect and say "work out X hours to receive Y benefit in your later years." There are short term rewards to exercising, ie endorphins or "runner's high" but I am guessing those are just hardwired rewards our brain gave us when we had to chase our food down for miles.

2 hours a day is a lot. Most of us do not live in a world where thats possible; between working, cooking, cleaning, sleeping, hobbies, down time, there's just not enough time to do it all. I can empathize with the researcher's quest to prove a "one-size fits-all" doesn't really work but who is actually surprised by that? All this article does is depress people that already feel hopeless. Keep doing whatever exercise you can, listen to your body, and just try to find some happiness in this world. Physical activity is a great way to do it, but if I have some set expectation that I have to meet it becomes a lot less fun and more like any other chore.