Strength Training is an important part of any exercise program. Most strength training programs include 8 - 10 different exercises designed to strengthen different muscles. A basic strength training routine focuses on the core muscles: legs, shoulders, chest, back, arms and abs. Most individual strength training exercises include 8 - 12 repetitions of a given movement, and anywhere from 1 to 3 sets, or series of repetitions. Beginners typically start with 1 set of each exercise, and advance to 2 or 3 over time. Often, strength training routines involved pairing different muscle groups, for example working out your chest and triceps on one day, back and biceps another day, and legs and shoulders on a third day. Since your muscles take about 48 hours to recover, you should plan to leave that long in between working out the same muscles. Strength training is most often done at a gym or fitness center, or at home.