If you can forget easily then you will have an easier and happier life. You will be able to focus more on positive things and make your life better than ever.
The people who are having a hard time in their lives can't forget easily. They are bitter, they have strong ego and they were always focused on the bad things that happened to them. They were full of dramas and they can't move on from the simplest things that bothered them.
If your boss scolded you yesterday then forget about it, if you will keep on thinking about it then your work will be affected, as simple as that. Even if he is the one who's wrong, don't talk about what happened to your co employees. Just keep on moving forward and look for better things ahead. There is no point in sticking with that ugly feeling, there is no point in getting sympathy from your co-employees and telling everyone how badly you were treated. If you will keep on making dramas then it will be very hard for you to make a progress and produce efficient work.
If you suck yesterday in your presentation or any kind of public speaking activity... forget about it as fast as you can, it is nothing and it is not the barometer of your greatness. It is normal to crumble, get pressured and unable to show your skills. Don't be hard on yourself and just focus on the next opportunity. If you will keep on thinking about your failure then your confidence will go down. There is always another day, there is always another opportunity to shine on the big stage. It is not the end of the world so don't make it a big deal, it is nothing but another funny story in your life, it is nothing more than that.
If someone hurts you or disrespect you from the past... forget that person easily and never think about revenge, you will only get burned if you are planning a revenge. You will feel heavy, it feels like there is a huge blockage in your chest and you don't know what it is, you will always think about that person and that will ruin your life.
If there is something bad that happens to you, may it be small or big... forget it, if you can forget easily then you can live a better life and see the better things that are bound to happen. Always remember that what happens from the past cannot be changed anymore even if you make a revenge or cry about it, the best thing to do is just move on and try to make your life even better. You can become happier if you will learn to let go of the things that are stressing you, don't talk about it, don't feel bad about it.