5. Getting Stuck in a Rut. Muscles have memory, says Pillarella. They adapt, they adjust -- and our bodies plateau.
"If you always use the same piece of equipment, your body will become adept at that type of exercise," she says.
Instead, mix it up.
"If you always use the treadmill, get on the bike," Lockhart suggests. "If you always work at the same pace, practice doing intervals -- shorter surges to build your upper-end capacity. It'll jog the body's systems -- make your body wake up and have to regroup."
To add intervals, increase incline or speed for short periods during cardio exercise, says Trese. With your strength routine, change the order of the exercises or rotate from machines to free weights.
"With more versatility, your muscles won't be prepared and your body will not automatically know how to respond," Trese says. This will keep things fresh for your mind, too, she says, "making workout routines less boring."
Lockhart advises varying your exercise program every six to eight weeks if you're working out consistently. This is enough time for the body to benefit from the routine without getting complacent.