I put on muscle easily. I like to do weights in addition to cardio, but I always end up bulking up. I do 2 or 3 sets of 15-25 reps with the lowest weight that provides a reasonable challenge--anything lower and I wouldn't even feel a thing. I thought less resistance, more reps was the formula for toning, is this incorrect? I'm training for a half, so I only have about 30 minutes a day to devote to non-cardio.