You should be able to get a very good work out in an hour. People who go to the gym for 2 or 3 hours at a time are just starving themselves (muscles).

One of the most over played things to do when you get in the gym is hit the treadmill. Get warmed up and then hit the weights. A trainer I go to church with says that you should hit the weights first before doing any cardio. Because the first thing you burn is sugars and then fats... people who do cardio first will burn thru the sugars (leaving them feeling tired/sleepy/drowsy) and then try lifting... If you do weight training first, you'll burn thru the sugars first and then your cardio will burn the fat at the end.

I've lost 30 lbs going this route (of course dieting also). My diet for myself is easy and I think anyone can do it... its just portion control. Eat what you want but just watch your portions. Now of course if at all possible, try to eat healthier and stay away from FAT FAT FAT foods, but don't limit yourself on ONLY eating what is healthy, otherwise it'll be too hard to stick with the diet. I've found (for myself) that portion control works for me and I continue to eat what I want... pastas, taco bell, KFC, occasional McD's... just portion control yourself... oh and get into counting calories.