I've recently started exercising (bout a month and a half ago). Every other day I do jumping jacks, crunches, curls, and lifts. I'm up to 2 sets of 35 jumping jacks, 19 crunches, 20 curls, and 20 rows with a backpack full of books and a 15 pound weight that I found at goodwill. What other exercises should I add to my routine? Am I missing any major muscle groups? I know nothing about exercise except that you're supposed to take a day off between workouts.