Want to develop stronger, more defined arms? The kind of vanity muscles that fill out the sleeves of a T-shirt or polo? Focus on your biceps, triceps and shoulders. This quick and easy-to-master workout guarantees bigger arms with all the right definition. And best of all, it only takes a few minutes. Known as a tri-set, you perform the three moves back to back with as little resting as needed for five minutes straight. Start out with five reps a piece, then each time you repeat the workout, try to do one more rep. You're sure to see fast results.