You should be a pro by now. Pick one of the 30-minute cardio options, then wrap it up with your 10-minute stretch. If you performed the AMRAP series earlier in the week, consider doing it again to see if you can beat your previous record, knocking out more rounds in each pyramid than you did before.
Option #1: 30-minute walk/jog sequence
Alternate between two minutes of jogging and one minute of walking for the full 30 minutes. If jogging is completely out of the question, alternate between two minutes of speed walking and one minute of walking at a moderate pace.