Generally when people go to the gym they have a goal. Whether it is to get stronger and gain mass, get toned, lose weight, or whatever it is that person knows what they want. The issue is that those people may not know how to achieve that goal. There are different types of training for each type of goals. If you are trying to build muscle and gain mass you want to go more of the strength route; if you are trying to lose a bunch of weight you want to be sure to use several different styles of training.
If you are someone who wants to gain mass and put on lots of muscle then you are looking to build strength. In order to do this you want to focus on lifting more weights and training muscles rather than overloading with lots of cardio. When you lift for strength you want to start isolating muscles and also doing core lifts like squat, bench, deadlift, overhead press, cleans. When you perform these lifts you are using a compound of different muscles, meaning that you are using more than one muscle to perform these lifts. If you want your numbers among these lifts to go up then you need to focus on strengthening those muscles that work together for those lifts. When working on these muscles you want to focus on lower reps as well as lower sets. So if you are training for strength on bench you would want to do three sets of five repetitions, instead of five sets of 10 repetitions. Training for strength you want to focus more on heavier weight and lower rep counts. Going for strength you should be lifting weights around four to five days a week with a little bit of cardio on one of those days.
If you are someone who is training to look better and have more definition of your body, you are going to want to take a different route. If this is your goal you are going to want to mix weight lifting, using high reps and sets, as well as some cardio. Notice I say some cardio, when you perform too much cardio you are actually taking a chance of losing the muscle you already have built up. When you perform weight lifting you are going to want to focus on using lighter weight with higher repetitions. So you want to possibly use sets of five or six with rep counts at around 12-15 maybe even up to 20. You will also want to mix in cardio about three days a week, but not doing too much; try limiting your cardio to no more than about 30 minutes a day.
If you are someone who is wanting to lose a lot of weight and rather quickly you want to take a different route than the previous two discussed. You will want to focus on more cardio and less weight lifting. You would want to do cardio about four to five days a week along with weight lifting about three to four days. Cardio burns fat faster than just lifting weights, but incorporating weight lifting into your workouts will give you more definition and some strength when you get to your goal weight, or end goal.
An overarching piece to training is eating and sleep. You want to make sure that you are eating the right way as well. If you are someone who wants to gain strength then you want to eat lots of protein (chicken, beef) and veggies as well. Eating junk foods, pizza, burgers fully loaded, chips, dessert, etc, will deter you from seeing results. Sleep is also a huge piece, you want to aim at getting about eight to nine hours of sleep a night to make sure that you are well rested and that will turn into more energy throughout the day and throughout your workouts. If you are averaging about five to six hours of sleep you are actually going to hurt yourself in the long run and that could also lead to injuries.
Training the right way will maximize your results and ensure that you are meeting the goals that you set for yourself. If you really want to see changes for yourself then you need to change how you work out. Once you start training to meet your goals and focusing on that type of training and those goals, the quicker you will get to where you want to be.