Thank u ... u r right ..n they are pros n iam just starting .... n even ma wight dont help me ..now i walk for 60 mins .. n i will try yoga
I'm assuming that you're just getting started with an exercise routine, so you're probably not very limber and your muscles aren't very strong. The girls in Jilian's videos are "pros". They exercise daily, so their bodies are used to exercising.
It's best to start off exercising with something not so strenuous, then work up as your muscles get stronger. Yoga is a good beginning exercise, as is walking.