I think push-ups, sit-ups, Jumping Jacks, Running, and then pull ups etc. are the best way to build muscle. Weights make you move in different directions than you would normally move. Like the normal punch. It's an extension of the arm. Using weights makes that movement kinda awkward most of the time.
For Tae Kwon Do I do 50 for each for a warm up, then go to running and then to kicking and curriculum. I personally hate weights etc because there useless. Sure you get huge muscles, but you don't have the endurance.
Rule of Weights:
More Repetitions less weight = Tighter, leaner, and higher endurance muscles
Less Repetitions More Weight = Bigger, bulkier, and less endurance muscles
What good is does it do you if you can bench press 200 pounds but you can't do it more than one time, or hold it for a minute?
The good thing about fitness is that you can learn things like fighting, while you practice. Get some boxing gloves and practice on something like a support beam(Hitting them too hard scares the hell out of you and shakes the house). Don't hit hard, just tap and practice on speed. In no time you will be sweating and have learned a bit of bunching combos.
Also be sure to work the lower body, not just the upper body. The foundation must be stronger than the upper body to support it and give it more power.
Lengthy post, but I like staying fit and talking about it. It's almost sad how people in my High School complain when they do 10 push-ups! That and the obese rate in my school is through the roof!