Raised arm circles is another one of those exercises you can quickly tailor to your available time. Do it fast, for a minute or so and it's a quick shoulders and arms workout. Do it for five minutes or more. alternating between slow and fast circles and changing the direction of the rotation every minute and it becomes a medieval torture exercise that would have you confess to anything (if you had anything to confess about).
What's involved: Shoulders (primarily), triceps, chest, neck muscles (splenius, trapezius and levator scapulae to be precise).
Powered by: Shoulders (deltoids).
Tip: Keep your arms absolutely straight and at the exact height of your shoulders.