Keep challenging your body in new ways to get the results you want from your treadmill workouts. (verywellfit.com)
You're still focusing on all your major muscle groups, but you're progressing by challenging your body with new exercises and more resistance. (verywellfit.com)
The best way to get firmer, tighter muscles, that toned look most people strive for, is to start challenging your body by using weights. (fitbodyhq.com)