I love lifting weights, but only when no other means of building muscle is available to me. The human body was not meant to pick up heavy metal objects and put them down again. This is why so many people find themselves frustrated when trying to gain weight in the gym. The body can recognize the monotony of an activity, and simply stop responding to it. I've been training in martial arts for many years now, and the best way I've found to stimulate my muscles is through an intense grappling session with a partner. Submission fighting is a full body workout, and has a lasting effect on overall body strength. Not to mention that the mind recognizes it as a more "real life" situation, and will push the muscles excert themselves to an extent normally possible when lifting weights. You can grapple and either lose weight or gain mass, simply by adjusting food intake. After several years training in brazilian jiu jitsu, my muscles simply stopped responding to pumping iron. Now, that familiar burn can only be achieved from a grappling workout (not that I'm saying the "burn" feeling indicates progress), and I would not have it any other way, as I am building both skill and strength as a workout. When I do lift weights, they are applied in strengthening a bodily motion that is directly connected to a martial arts technique. Lifting weights builds some strength and burns calories but you are not gaining any skill in your martial arts as you do this. Just imagine how good you would be by now if you had applied all that time spent lifting weights toward your martial arts training instead. Just a thought...