Lifehacker has a infographic giving research-based workout exercises that will work your whole body. The best bit is that you apparently can do the whole thing is 7 minutes (30 seconds per exercise, with 10 seconds rest between them).
The exercises are:
- Jumping Jacks
- Wall Sit
- Push Ups
- Abdominal Crunch
- Chair Steps
- Running in place, lift knees high
- Push-up and Rotation
- Side plank
Apparently your discomfort should be around 8 on a scale from 1 to 10.
The original source is The American College of Sports Medicine Health and Fitness Journal.