Thanks for the quick replies.. I did crunches in place of squats.
On Level 4 Day 1, I did 10 crunches instead of 6 squats - is that fine, or should I do about 2x the number of squats?
Also, I've been moving up levels once I got day 2/3 to around 10 min - just read somewhere on the forum that I should move up once I hit 5 min for day 3.
Should I drop down to level 2 or 1 to get down to 5 mins for level 2/3? That seems a bit too fast!