That's actually what my trainer has been telling me. My workouts with him are only about 45-50 min of warm-ups and weight lifting. He keeps warning me to keep from doing more than 2-3 cardio workouts per week. My typical workout week--Monday: compound weight exercises (develop multiple muscle groups), short run; Tuesday: target upper body, some abs, walking (steep incline treadmill); Wednesday: target lower body, some abs; Thursday: w/trainer in studio, exercise varies, teaches me more techniques for muscle "confusion"; Friday: target upper body; Saturday: outdoor calisthenics; Sunday: cardio or rest.

I know there's always news reports and even doctors telling people to do at least 30 minutes of cardio at least 3 times a week. However, if you're generally an active person throughout the day (walking around the office, running errands, going up/down stairs), you're probably getting this amount of cardio already. I know I walk a lot even though I have a desk job. I run up the stairs multiple times a day, my car is parked far away, I walk briskly everywhere I go so this is already burning calories--something you don't want if you're trying to gain weight. I haven't felt as if I'm any less capable of running several miles now that I don't run as frequently (muscle gains help boost power and speed and keeps fatigue down). So unless a marathon, triathlon, boxing, soccer or some other long endurance sport is your goal, then all this cardio you're doing is a waste of time and calories that you're trying to stuff down every day for weight gain.

My trainer also has me doing multi-planar warmups instead of jogging/walking to warm up. These seem to be more efficient since they not only raise my heart rate but also stretch my muscles while in motion. I used to only do static stretches, then some cardio, then hit the weights, but that only wasted energy I needed to lift as well as didn't really warm me up. This also helps cut down on workout time and can help keep your exercise to 45 min if you're short on time.