Ok, I'll admit that, off of the tennis court, I am probably one of the laziest people out there. I will hit for 6-8 hours a day if given the opportunity, but try to get me to go to the gym or go for a run, good luck! So, I've been thinking of ways to get past my laziness and was wondering what muscles I'm missing if I stick to a regimen of sit-ups and crunches? In other words, what lifts will I have to hit the gym for? I've searched, but there are so many options and I'm not a weight-lifting guru (nutrition on the other hand I have a pretty good knowledge base). I know this sounds pretty infantile, but I'm trying to figure out the best use of my time due to the amount of schooling/extracurriculars I am participating in (which leaves me with little to no social life... ).