It would require many, many hours working out in a gym. I think most of the really pumped up guys are heavy into HGH or Human Growth Hormones. Using these HGH injections, muscles can get very large without extreme workouts. They are known to carcinogenic but many people take the risk for the big payout now.
Good lcuk and stay clean.
Millard
The only way is to workout (lifting weights). Even then there is no guarantee that you will look like them. You would get stronger yes, but the amount of mass you would gain is also determined by genetics not just working out.