Engage

This is a simple but brutal one.

Adjust both total cals AND burpee box jump (reps and/or height/ style burpee) to allow this to be done in under 20 minutes

Burpee bx jumps should take about 40 seconds - these should be where the 'intensity' is, while the bike should be a steady, tough grind

Find a variation that allows you this intensity - this means you could modify the burpee and/or the box jump height