Try the Olympic Sport of Racewalking
Yes, racewalking is actually an Olympic sport. Yes, it is pretty hard. And yes, it can be extremely intense.
It is also becoming a more popular lunchtime past-time for people who want to get some quick intensity without having to run around their office building.
Check out the video and see if it’s right for you. One warning; You need to have a decent amount of self confidence to walk around in public like a race walker. You will def look very silly to some people.