I know we all have to work hard at getting in our gym time, so why do so few of us work hard once we get there? If you are going to go, you should make it worth your time. Make yourself sweat, get your heart rate really up there, make your muscles burn - even shake at times, otherwise it may very well be time wasted.
When you are at the gym you need to watch your form. Not only with the free weights and weight machines, but the cardio machines as well. I see people on the treadmill walking at 5 miles an hour (which is a super fast walk) at a 15% grade (which is a super steep hill) but are holding on to the handle with both hands. Let me tell you, you are burning less than half of the calories you would if you would let go and not helping yourself get any more fit. That goes with the stair master and stepmill as well. If you think you are really doing something because you have the level at level 15, but all of your weight is being supported by your arms - you aren't. You might as well go home.
In my weight class I go to, we work on all of our muscle groups and mix in cardio as well. Most people in the class are using the same weight on the bar at the beginning as they are at the end. That means they are squatting the same amount as they are bicep curling. PEOPLE PLEASE. Your leg and butt muscles are about 5X stronger than your biceps. If you are curling the same amount you are squatting - again, you may as well go home. Also, if you have been going to this or any other class for a significant time frame and going consistently, you should be able to increase your weight over time. If you are doing the same weights you started with 2 years ago, hmmmm are you pushing yourself very much?
I may sound a little harsh, but people always make the comment to me on how they go to the gym all of the time and nothing ever changes. You have to challenge yourself every single time or you are just not going to see the results you want. Make your gym time worth the effort it takes to get there.