1. Burpees!

Ah yes, the exercise everyone loves to hate and hates to love. Start from standing jump back into plank position, perform push up, jump legs back up under shoulders and jump into the air. If any issues with knee joints just step instead of jumping. 
20 seconds of work, 10 seconds rest then proceed to next exercise

 

2. Plank holds

Alternating leg hand out, right leg extended, hold 20 seconds per side. 

 3. Mountain climbers 

Can be performed elevated as pictured or from the ground in a plank position, ensure back is nice and flat.
20seconds work 10 seconds rest going to the next exercise

4. Squat jumps 

Sink into hips and jump straight into the air, ensure a soft landing with knees not falling in. 
20seconds work 10 seconds rest moving on to the next

Perform one set of stairs & then rest