Lifting weights can be the most helpful thing to a martial artist. But you have to lift SMART! If you lift for any reason other than your martial arts, you may get some unwanted changes. Weight training to look good or to bulk up is not a good idea for the martial artist. Train for the muscles you use in your techniques. Train for endurance. You don't have to go to failure like in bodybuilding, because your goal is to build dense, hard muscle, that will not restrict movement and give you great speed and power. Also, bodyweight exercises are always a plus. I love pushups. Handstand pushups, fingertip pushups, one-legged squats. Sit-ups. Theres no way you'll get bulky from bodyweight. Also, incorporate some isometrics into your training. Isometrics do not add much bulk and can give you a lot of core strength. They will give you a great amount of strength and speed which will result in powerful strikes. Just remember, when weight training for martial arts, think martial arts, think about function. Oh, and keep with regular cardio and stretching!