If you are working out for X minutes and still losing weight keep doing that, but when you plateau you will have to switch it up and work out for X minutes + X more minutes... if that makes sense? About an hour to an hour and a half is a good time frame, I don't know many people that want to spend two plus hours on cardio alone.
As for shoulders (I think you're talking about lateral raises?) it takes time... if you can do the sets without having to rest you need to up the weight, if you need 30-1minute of rest in between sets then keep at it. You need a challenge when lifting, that being said good form and light weight is always better then bad form and heavy weight... keep pushing yourself and you'll get use to it. Try switching it up and doing some upright barbell rows, shoulder fly's, and incline presses for a few weeks and go back to the lateral raises to see improvements.
I know sometimes I get stuck doing one exercise for a few weeks and try and base my improvement off of that one exercise, but I just end up getting so familiar with that exercise it becomes easy and I'm not really "improving" even though it feels that way. I like to switch it up each week and then go back and see if I can lift more
Last edited by Urbanmule; 07-27-2011 at 10:10 PM.