7. Resting Too Long. The machine you want to use is occupied, so you grab a towel, get a drink of water, run to the bathroom -- and the next thing you know, 10 minutes have passed.
To avoid such time-wasting, rest only 30 to 90 seconds between strength exercises, says Comana.
To maximize time, alternate a set of exercises for your biceps with a set for triceps, he says. That allows you to shorten the rest interval in between -- while one muscle group is working, the opposing group is getting active recovery.
You can also save time during your warm-up by mimicking exercises you'll be doing in the workout. For example, Comana says, if you plan to work your legs by doing lunges and squats with weights, warm up with high knee steps, butt kicks, lunges with a twist, and sumo squats.
"Perform movements that are the same as you'll do in the exercise so that you can better prepare the body for the exercise," advises Comana. "You're warming up the joints while tying into the neuromuscular system to create movement preparation