Mainly because he gets paid ridiculous amounts of money to look good on screen.
Also (despite cgi possibility) vascularity in the last few movies didn't appear natural for a 40 year old.
Possible he is natty, but highly unlikely imo.
Agree. With 10s of million of dollars on the line of course you would.
Did hear in an interview he said he rang up the rock for "training" advise. Lol.