Try a slight variation

- Burpees are considered one of the ideal all-around exercises
  (see http://www.nytimes.com/2011/04/17/magazine/mag-17exercise-t.html?pagewanted=all).
- Chair steps seem more like lower body, and don't do much for me since I cycle often
- Replace one of the planks with a superman back stretch, which is more useful for me (I spend a lot of time sitting)