Don't Be Married to Your 6-Pound Dumbbells
Certain muscles are stronger than others, so that means modifying your routine with different weights in order to target your muscles effectively. I keep a set of six-, eight-, and 10-pound weights on hand, and depending on the difficulty of the exercise and the strength of my muscles, I change up the weight. You'll know the dumbbell is the correct size when your muscles become fatigued after 10 to 12 reps. Follow that rule when lifting and you'll spend less time pumping iron but will achieve quicker results.