Distinctly David: The Good Morning is a basic lower-back warm up that can be used at all levels. At the beginner level, concentrate on getting the form down and focusing on stretching out your lower back and hamstrings. As your level of proficiency improves, you can add weight by placing a pair of light dumbbells behind your head.

Jumping Jacks
Muscles worked: Thighs and arms
Time: 1 minute

David's Platypus Walk
Muscles worked: Butt
Time: 30 seconds

This is an awfully silly looking exercise but it will get your heart pumping and quads burning.

Sit into a squatting position with your hands behind your head, your knees aligned with you toes and your butt sticking back as far as you can.

Keep your core tight and walk forward while pushing off with each heel. If you perform this correctly, you'll look like a platypus -- and your glutes and thighs will be on fire.

Make sure to sit back in your heals. Do not step too far forward or you'll stress your trailing knee.

Shadowboxing
Muscles worked: Shoulders, back, arms and abs
Time: 1 minute

You can shadowbox with or without weights. Hold light weights in each hand, and throw a series of punches. Make sure not to punch so quickly that you hyperextend your elbows or shoulders. Throughout your workout, keep your abs tight and your shoulder blades retracted. The tighter your core, the more effective shadowboxing becomes.