If you'd like to try this as a formal meditation here's some ideas & imagery that might help. I always recommend meditating after some asana (physical) practice because it gives you time to focus on your physical body & then forget about it. I also recommend making sure you are in a place where you won't be disturbed or distracted.
Sitting in a comfortable position, start by focusing on your breath, letting the inhales and exhales, the expansion & contraction, take up all your thoughts. Once your focus is complete, allow it to move to your heart. Take inventory of your emotions, imagining sorting through a card file if you like, or searching through a pile of clothes, just noting what you find in your heart. When you come across a sad, angry or unhappy emotion - just pick one - imagine yourself taking it out from the rest & bringing it closer so you can look at it. Allow yourself to feel the emotion, you don't have to relive the experience that caused it, just experience the feeling. You can visualize that feeling like a little flame, flaring up, growing, running out of fuel, dying down and eventually going out completely. Imagine the ashes blowing away. You could also try visualizing the emotion like a flower (I know, it's not a good emotion, but it could be a weed flower, like a dandelion if you want), imagine it growing out of your heart, getting bigger, blossoming and then slowly dying, the petals withering and falling off, the flower wilting and decomposing back to the earth. You can make up your own visualization if you want, but the end of this visualization is the most important, letting the feeling die out and letting yourself release it. Focus again on your heart & feel it a little stronger & healthier, maybe a little cleaner?
I think learning this skill is life saving. Allow yourself to experience & release rather than wallow in or repress & you'll feel a big difference.