I discovered this by accident several years ago and thought I would share it. This is a good exercise to help practitioners alter their perceptions. Once you can do this then you now realize you can alter your perceptions of just about anything. You can make yourself feel good, make good experiences "greater" and you can alter even unpleasant things to make them be perceived better
In order to do this exercise you will need a song. It can be any song you like like and it can be played on anything, such as the radio, a tape cassette, CD player, or even a song online or on YouTube. Whatever your choice of song it is up to you.
Now sit down in a comfortable position and do some breathing exercises to calm and center yourself. Get into a relaxed mood. Now, play the song.
I want you to listen to the song, the tempo, the beat. Then I want you to make it speed up, not by doing anything to the song, but by pure will alone I want you to speed the song up in your mind so that you perceive it playing faster. This is not impossible. If I can do it, so can you.
Now, once you reach the point where you can speed the perception of the song up, then do the opposite. Slow it down. Then bring it back to normal.
I'm not saying you will be able to do this the first time you try it, but you just might! Even if you don't get it right away keep at it. Eventually you will and you will be shocked that you have that power!
Once you realize you can alter the perception of the music, start applying this technique to other situations. For example, if you are in a boring class at school, use it to speed it up. If you are enjoying a movie, use it to slow it down, etc.
Have fun! You are far more powerful than you realize!