I am skinny and I have a six pack and good biceps from situps and weights mainly. (I also do other muscle building exercises and biking)

My diet is nothing special but I eat a lot of fruit as well as junk food. (not too much)

What should should I change?

Exactly as Schweppes says. Lee was physically gifted with a propensity of fast-twitch muscle fiber and a very compact but muscular build.

He also trained fanatically on top of his physical gifts.

So, unless you have a similar genetic background and similar muscle-fiber makeup... No way.

However, you can certainly be the best "you" possible... All that takes is hard training.

Step one: Be Bruce Lee

Stock up on healthy fatty foods with omega such as fish to gain weight

Cut the junk food ! And you can't have a body like someone else