30DS question.

theroadto100

How did you guys decide when to move up a level? I'm on day 5 right now, on level 1 and the cardio/abs are pretty easy for me. I can get through both without stopping and don't have to do the modified versions of any of them. But I'm still struggling with the strength. I have to take a break or two during them and do mostly modified versions. So should I continue to stay on level 1 even though the abs and cardio aren't a challenge or move up even though I'm not ready for harder strength exercises?