I thought I'd pop in and offer some "insight" on exercising. I was helping a new person to the gym the other day, and it occurs to me that many people don't really focus on working the muscle in regards to what it's function is. So I'd like to give a few examples.
Almost every muscle in the body falls into a "pushing" or "pulling" muscle. While thinking about that, consider this...
Triceps: A two very common tricep exercises are tricep extensions (in a downward motion) and skull crushers. It's important to know why you're doing them. You don't do them to "lift" or "push" the weight. The tricep function in the body is to extend your arm. While doing these exercises, focus on doing that task. Extend your arm. Don't "push" anything.
Biceps: Most common is the bicep curl. Again, don't focus on "lifting" the weight. Focus on contracting your arm. When you do that, with no weight, your bicep naturally flexes. We don't pay attention because there is no weight load on it. So contract that arm, flex the bicep. Don't "lift" the weight.
Chest: Bench press! The chest is a pushing muscle, and it's purpose is to drive your arms forward of your body. Focus on squeezing the chest and doing just that. Importantly, this is one of three major "full body" exercises. It involves shoulders, triceps, traps, forearms, and core. Push the weight as intended, but remember that everything else needs to work too. You have to focus on extending your arms, tightening your core, and flexing the traps as well.
Quads: Squat/leg press. The purpose of the quad is to, like the tricep, extend the leg. Don't focus on lifting the weight, focus on standing up/straightening your leg. Squats, like bench press, is a full body workout, so it requires some other flexing
Hamstrings: Ugh. Leg curls. Kind of. But the really good one... Romanian (stiff leg) deadlift. What's the point of the hamstrings? To contract your legs just like a bicep does for your arms right? Not really. Although a small portion of your hamstring provides that function, its biggest purpose is to push your hips forward. Ever seen an athlete pull a hamstring while curling a leg? Nope. They pull them while running and jumping, two things that your hips need to be driven forward to do. Learn how to Roman deadlift, and you'll see what I'm talking about
Back: rows. The back is a pulling muscle too, but it's goal is to bring your arms towards the back of your body. As you do your rows, once the bicep work is done, remember that your back is bringing the arms back after that. It doesn't matter if it's rows or pull ups, wide grip or narrow grip. It does the same function. Although, remember that exercise and grip will put more/less focus on which group of back muscles you work.
Shoulders: DB raises of many kinds. The shoulders are used to bring your arms up from your sides. They are not complicated, but it's important to remember when doing some of those lateral raises or reverse flys. Mil press is another exercise that uses them too, but works with the traps while doing it.
Abs: These are the interesting ones. They are the muscle group that is not responsible for pushing OR pulling. Their function is to protect your organs, but more importantly, your spine. Abs benefit from both contracting AND extention. And they benefit from it because you have to flex them for both. They flex to contract, and they have to flex to extend in order to support your lower back and spine. Take advantage of both.
So why is this so important? There is something refered to as a mind-muscle connection. This connection is the sole reason why you fall into "muscle memory" problems. When training, you should be focusing on what you're exercising, not the weight that you're trying to lift/push/pull. This helps you make a more solid connection, and work that muscle, instead of letting your body naturally throw any muscle into the mix to try to help out. And why is THAT important?
Form.
Results.