[krzat]

There is really nothing magical about metta. It's all in consistent practice.

1. You visualize a cute bunny (for example).

2. You recognize that visualizing a cute bunny makes you a bit happier.

3. You realize that you can influence your mood by visualizing cute things.

4. You train it to make it stronger and more reliable.

[denton-scratch]

Sorry, but I don't think metta amounts to feeling "a bit happier" or "being in a good mood".

Metta is one of the four Brahma Viharas (foundations of Brahma). Another is karuna, or compassion; wishing others not to suffer. The standard practice in Tibet for generating compassion is called tong len ("sending and receiving", sorry, I don't know any Sanskrit word for it). You imagine someone else's suffering as a black cloud, breathe it in, and breathe out all your goodness and happiness as a white cloud, which you imagine going into them. It's a simple bolt-on for ordinary meditation on the breath. [Edit] If you have a real, suffering person to practise on, I was told that helps a lot.

Practising tong len is liable to cause depression in the practitioner, or so I was told. It's not tantric, you don't need permission to do it; but it's probably not a good idea to try it unless you have an experienced meditation instructor.

"Feeling good" is not a sign of progress in meditation.

[krzat]

I'm sure there are well established practices in Tibet but IMO there is nothing special about them, which is why there are multiple schools of Buddhism instead of just one.

I had a real suffering person to practice on (me) which is why I'm quite certain about what I wrote. If you have capability to improve your mood on demand, your entire approach to life changes. You can be selfless, take risk, work long hours, even if entire world collapses, you will always have metta to support you. This is how I understand equanimity at the moment.