Thanks, 2h is a bit too much for me, so what I do is about 3-4 10-12 mins walk-sprint walk reps. Basically half walk (3.5m/h) and half sprint-walk (4.4m/h). I wish I could do more but my joints are not really good.

Just walking is better. You get a steady burn. If you do high intensity you burn calories for a good while afterwards. Mild intensity doesnt do much.