This ultra-quick workout targets the major muscles of the body for a quick, efficient workout. This won't take the place of a complete total body program, but it's great for maintaining fitness without spending a lot of time exercising. For this workout you'll need a light-medium weight resistance band and a chair.

Warm up with a few minutes of walking in place
Do each exercise for about 1 minute (add more sets if you have time)
Go slowly to really work your muscles
If you don't have a resistance band, use full water bottles as dumbbells or nothing at all

Pushups
Pushups work your arms, chest, abs and back and you don't need any equipment. Do them on your knees (easier) or toes and keep your back straight (no sagging) and your head in neutral alignment. Keep abs tight as you lower and exhale as you push back up. Do as many as you can for one minute and move on.

Plie Squats w/ Resistance Band
Stand with feet wider than shoulders, toes turned out and resistance band stretched beneath feet. Keeping the band taut, lower into a plie, keeping knees in line (and behind) toes and curl arms up, lower back to 90 degrees and squeeze butt to stand up. Repeat for 1 minute.

One-legged Squat with Shoulder Press
Stand with right foot on band and left foot lifted a few inches off the ground, holding onto a chair for balance. Bend knee and lower into a slight squat (butt back, knee behind toe) then raise right arm straight up over head. Do about 16 and switch to the other side.

Deadlift with Band Row
Stand on band and pull it tight, hands in front of thighs. Keeping back flat, tip from the hips and bring hands down the legs to mid shin. While you're down there, bend elbows and pull them up to your ribcage, contracting the back. Tighten butt to lift back up. Do as many as you can bear and move on.

Tricep Dips
Find a chair or solid object and sit on it with hands next to hips. Move hips in front of chair and, keeping butt close to the chair, bend the elbows and lower a few inches. Don't sink into the shoulder or lower past 90 degrees. Do a whole bunch and get ready for your last exercise.

Side Plank Ab Twist
Lie on your side and push up so that your body is supported by right hand (or bent forearm), feet stacked. Straighten left arm and sweep it down, twisting your body and turning shoulders towards the floor (hips don't move). Do it on the other side and then hit the beach.