Hmm, I've kind of been there as well, though not in the extent that he's at judging by your description. Still, exercising really got my blood flowing again, or finding more impressive physical things to achieve, like cycling for 180 kilometer on a single day or participating in the
International Four Days Marches Nijmegen for the 4x 50 kilometer walk. It's things like these that give me the idea that I'm achieving something that a lot of people will never be able to do (with their mentality).
For me, the feeling of progress was lacking in my life after I was done with high school. Apparently this has to do with an addiction to games, but I can't be bothered to find a report about this. Doing crazy stuff like the Four Days Marches gave me a goal in life, apart from "Study, earn money, sustain myself, repeat".
Edit; be gone hyperlink!