Whether you lift weights, do anaerobic exercise, or run on the treadmill; you are to attempting to force your body to adapt to the new norm of your life. This is why your muscles get stronger, bigger, or more lean depending on the exercises you perform. Think of it like this: you’re body is a machine, and an incredible one at that. If you provide it with clean and healthy fuel, it’ll perform and have more energy; just like a automobile. The difference between your car and your body is that the more you exercise and train, the better and stronger it’ll become. It’s a machine that adapts to the strain you put on it.
If you run a mile around a track for the first time it’ll be exhausting. If run a mile again the next day it will probably be just as difficult or more so since your legs will be sore and full of lactic acid. On the third day, though your legs will still be sore, you’ll see that it’s become a little easier. Your breathing, although not dramatically, has become more steady and less painful. This is how your body adapts to new physical challenges in a short time. To achieve measurable results, you have to keep running that mile.
That being said, if you want to continue to see increased performance, you must be willing to push yourself. Unless your goal is to maintain (which is perfectly fine), exercising with what you’re comfortable with will never increase your strength or overall performance. This not only applies to weight lifting, but also a life lesson if you want to be great at something. You have to be willing to fail in order to make yourself better (just make sure you have a spotter). It’s important to understand that you’re training your mind just as much as you’re training your body.
This makes sense and may sound obvious, but many people, including people who live at the gym, forget what they’re trying to accomplish. More often than not, people go through the motions instead of actively trying to push their body to become stronger and better.
Next time you’re working out, keep this in mind: you’re trying to make your body and mind better. To do that you have to make yourself do things your not used to doing. Easier said than done, but by building healthy habits and routines, you'll not only see improvements in your body, but your mind too. You'll actually want to go to the gym! Use this mentality, and you will find the motivation to go beyond what you thought was possible, and reach new limits.