I don't want to toot my own horn, but I think you will love this ab HIIT cardio workout. Starting with a series of all-standing low (with high impact options shown), you'll get a good little sweat going and then follow that with a series of ab exercises on the mat.

Osteo-friendly options are shown for the ab series; this is the perfect little cardio workout for all levels.

Day 14 of the Unstoppable Challenge

Tools: nothing

2 x 30sec
Jumping jacks (alt: low-impact jacks)
Squat pulse & heel lift
Speed skater
1-leg deadlift
Repeater knee w/ twist
Repeater knee w/ twist
Side-to-side rope skipping

2 x 30sec
Mountain climbers
Supermans
Toe touch crunch (alt: plank)
Straight leg double crunch (alt: v sit)
Side plank side crunch
Side plank side crunch
Bicycle crunches