The peripheral vision means the ability you see from your central vision into the side vision. You could do the exercises of eyeballs often which may make your peripheral vision improve a lot. You could set the times your eyeballs move. Then your eyeballs will be active. You should do such eyes exercises often which may to some degree improve your peripheral vision.
Well, generally speaking, according to some experts, peripheral vision is very important in sports performance. And also, you should know that peripheral vision goes into your brain 25 percent faster than your central vision. By the way, about 20 percent of your peripheral nerves aid your ability to remain balanced. In common, you can try some exercises to relax and improve your peripheral vision. For example, you can concentrate on looking as far out to the side as you can while slowly taking deep breaths. In this way, this peripheral expansion exercise will relax the visual system. Also, you can try a form of meditation called Hakalau which was used by the ancient Hawaiians to practice focusing on peripheral vision. Anyway, just have a try.
It seems that you are not very satisfied with your peripheral vision. So, I do not know whether you have suffered a decreased peripheral vision. As far as I know, if your peripheral vision is impaired, you should take an eye surgery to fix the real problem because a decreased peripheral vision is a symptom of other problems. If not, you should just get more vitamins and healthy food that is beneficial to your eyes.