There is a practice to increase concentration
There is a simple meditation practice called shamatha in Sanskrit, shyiné in Tibetan, or Shikan in Japanese. You will learn to focus on one point or object. Thoughts will arise, but we practice not to play with the thoughts. You will not be bothered by your auto-generated thoughts. You gain control over your mind. Your mind becomes clearer and sharper. Then, it is easy to focus on one thing in this crystal clear mind. The intensity of focus is not comparable with the uncontrolled mind.
negative thoughts cannot control you anymore
If you achieve this skill, there is a big bonus other than increasing focus. You won’t be bothered by negative thoughts. It is the negative thoughts that make us overthink and become exhausted. You will find complete rest in this meditation. Actually, there are more big bonuses, but it is more joyful if you find them yourself. So, I should stop here.