Take up racketball. I just played my 1st league game, played the #3 ranked in BC (I'm a nub at this game) and just got fucking OWNED. Point being, by the end of the 45 minutes, I was beyond exhausted. I have never felt like that after doing 45 mins of cardio. And most racketball cardio is HIIT too! I'm looking forward to my 2 games a week!