When it's too cold outside or I can't make it to them gym, my favorite way to fit in some flab blasting cardio is going for a thirty minute run... up and down my stairs! Sometimes I add in twenty minutes of jumping jack intervals, man are those fun!
To make any workout fun I blast some heart pumping tunes. When I do jumping jack intervals I dance to the music between sets sometimes, it keeps me on my toes and having fun!
A great way to do intervals is with this video: