I LOVE fusion! I do this workout every week. It is so different from other workouts that I've done. I don't feel it in my abs the next day however, but I do feel it in my upper back muscles. There is no dread factor for me with this workout and I get better at combo 2 everytime I do it. I just did boxing for the first time the other day and I loved it too. I skipped the lower body drills because I have a sore foot right now and can't do the impact, so the workout ended up being about 35 minutes long which I think is perfect to add on to a leg day especially since it's mostly upper body. The punching combos were really, really fun and not too hard to figure out, and it gave me good DOMS in my shoulders. I haven't done kickboxing yet, but I watched it and unfortunately it doesn't look fun to me. I wil try it though, you never know.