Okay heres the first challenge, try to do all of it but no worries if you can't as it will be a great starting point:
Do all the following exercises for 1min, try not to have a break between exercises.
Lunges (back knee close to the floor)
Burpees
Pressup (start with full pressups, then frop to knees if needed)
Crunches
Bridge
Rest for 1min
Repeat above exercises for 30 sec
Rest for 30 sec
Repeat above exercises for 15sec
All finished