If you have FB he talks about it in the Tom vs. Time Docu-series put out on there during last years playoffs and SB. Short answer is that he barely lifts at all.
I watched it on YT, but every time someone posts it up it gets yanked right away. They couldn't keep up with it when it first came out so I was able to see each episode back then.
I'm not a fan of the Pats or TB, but I do find it incredible what he's accomplished and how he's able to still do it at his age. I thought it was done pretty well. He seems insanely down to earth for someone with that much money and fame. I grew up a huge Montana fan, and by most accounts he's kind of an arrogant dick in person.