I'm an on-again-off-again 30 Day Shredder. I typically do L2 now, and I can say, that it depends on the day as to just HOW hard it is...but it is always hard. The good news is, I modify less, I am doing the moves with better form, and I definitely see the difference in my body.
Soooooo, easy (unfortunately) isn't the goal. Effective is - and Jillian has that goin' on! Keep it up. Modify where you need to, and know that you'll always find it challenging, but you will improve & get stronger as you do it more.
She's a monster, in my opinion...but I love her anyway

. Anyone who can whip my butt into shape in under 30 minutes is a hero in my book!!