I know that one common practice among psychologists, trainers, and spiritual people focuses on "letting go." Letting go of emotions, memories, attachments, and feelings that really BOTHER us to the point where they become like venom in our veins, monsters in our dreams, shackles on our feet that don't let us move, and breathe, and feel hopeful and happy ever again. And sometimes they are not that noticeable - like a bucket full of trash in the dark corner of a big room. No one can see it, the lid is closed, you might even forget that it's there... But the smell!
Letting go? Yes. Definitely.
But ONLY after working it through.
One of the possible techniques is what Castaneda called "recapitulation." Going back to each particular memory, feeling, person, or situation and re-living them in your mind while performing special breathing exercises. What this does is it takes away the emotional component of that event in your life and returns to you the energy you have wasted back then (while giving back the unneeded energy you took from that event). Basically, it severs emotional and energy attachments which formed in the past; thus, the practitioner's energy no longer drifts toward that event, person, or situation. The memory is still there, life experience is still there... but it no longer devours the practitioner. It becomes like an old film. You look at the film and recognize that it's about you, but what the film shows no longer makes your life unbearable.
Castaneda is not the only one and definitely not the first one who described this technique. And neither were the Toltec peoples. It was mentioned in Buddhist writings and in many other ancient sources, some of them hidden from most people. A person who used to teach me has another method of "recapitulation", but it's called differently and involves very intense physical and mental exercises to achieve the same or better results (as mentioned in Castaneda) in very short periods of time.
Imagine, Castaneda's method would take at least 2 years to cleanse any average middle-aged person. This other, rougher method would take only days. But the thing is, in order to perform it one must be in top physical condition since it comes from the times of ancient assassins (no, not the computer game ones, the REAL ones) whose training and physical abilities far surpassed those of any modern athlete.
There are other methods and sources. I, for one, like to try out and combine things. I think that if you are a true student of life and martial arts, you can watch your own mind and body and the world around you, and come up with what works best for you. That is, no point to argue that Castaneda's method or Buddhist method or any other method is the best. It doesn't matter. PRACTICE will show. And practice - implementing any teaching or theory in real life - is the only thing that matters.