Holding grudge is a state of mind where we get sidetracked by thinking of just our own considering no one else’s purpose and it is to some extent reasonable. It may be induced by some bitter experience of past or it may be also an outcome of past anger. This grudge sometimes makes you feel that you have complete command over yourself and there is no other to take away from you. In some cases, it is a rational to hold grudges but everything can not be judged by rationality. Benevolence is something for which the earth still exists. You should also learn this lesson from the nature.

We hold grudge because we believe in self-identity. We want to get stuffs personally and modify them according to our choice. When these preferences are violated, we get outrageous and that is where grudge starts to develop inside us gradually. We always possess a sense of comparativeness and we believe if we let go the grudge from us, then we will be proved wrong. Our sense of individuality makes us hold grudge for a long period of time. We can not let it go because it makes sense to us.

You should not hold grudge for long time because people are meant to make mistakes. At point of life, you should be kind and feel compassionate. Life teaches the same lesson. If you stuck with the grudge, it may bring a halt to certain part so your life. And the person whom you are grudged at may have changed themselves. So there is no point to uphold the ill feelings. Let it go, it will make you feel lighter. Life is already jammed with different types of hassles, disruptions, difficulties; so it will be pretty much helpful if you let go off the grudges that keeps bothering you over and over again.

Luckily, this topic can be significantly improved with hypnosis and clinical hypnotherapy.
Here are the two most suited choices:
Don't Hold Grudges