Intensity is the key to getting serious results on any weight-training program. You know what doesn't help you get results? Excuses like this one: "I train by myself, so I'm not able to lift as hard as if I had a partner." Nonsense. When you're training by yourself, you can hit the weights as intensely as anyone else. Just blast some inspiring music on your iPod and utilize the following intensity-boosting techniques, handpicked specifically for the guy or girl rolling solo in the weight room.