Keeping rooted in the present in the face of past realities

Kashalha, as vipassana is a too broad a word encompassing many aspects of Dhamma, I would recommend this one meditation, that can be done when you are walking, sitting, lying, or any other posture that when sleeping. It is called Sati Sampajañña. Alertness and awareness come under the Pali word, sampajañña. Sati means keeping something in mind, like remembering to stay with the breath, remembering the various things that help in the training of the mind. Our happiness, our lack of happiness, depends on our actions. So that’s where we focus our attention. That’s what we should keep in mind. This is called dhammanussati, keeping the Dhamma in mind. This is why the Buddha has us listen to the Dhamma, read the Dhamma. Whatever thinking that you do, it needs to be through the Dhamma.

When you create a frame of reference here in the present moment, there are lots of things you can tune in to. You can choose the body in and of itself. You can choose feelings, mental states, mental qualities in and of themselves. Those frequencies are on the path. Other frequencies are off the path—there is such a thing as Wrong Mindfulness, you know. Our meditation consists of choosing the frequencies most beneficial for the mind.

Whenever your thoughts go to recollecting your past incarnations, try to get them out of your mind, as they are a-Dhamma. To be consciously forgetful in that way requires an act of mindfulness—in other words, deciding which level you’re going to tune in to while you let everything else go for the time being. Of all the sensory input that comes in at any one particular moment, you make a choice of what you’re going to pay attention to, what memories, what frame of reference you’re going to bring to that particular moment. And it’s an important mental skill to be able to shift your frame of reference as necessary.

Being mindful means being very deliberate and clear about what you bring to whatever you’re doing: what you’re going to remember, what you’re not going to remember, what you’re going to recollect, what you’re going to let go, which things are useful to recollect right now. If you wanted to, you could sit here and spend the whole hour thinking about facts that would make you totally miserable, but what does that accomplish? We’re sitting here to think about things that are useful for the mind, so remember the things that are useful for the mind, that will help it develop. As for the other voices coming in and out of the mind, listen to the ones that are helpful and ignore the ones that are not. You can be selective.

This way, mindfulness becomes a quality we can apply to everything we do. And instead of making us unable to function, it actually heightens our ability to function, because we understand the process that the mind goes through.

A lot of people are recommending Vipassana but this is incorrect.

Samatha (calm-abiding) is the appropriate one.

Why?

Because you need to bring yourself to this present moment, centering on your breath.

Then, only when you make an intention to remember these things will you remember them.

Read Mastering the Core Teachings of the Buddha for more information regarding this tip. There is an explanation on there on a single page...

Do vipassana, a retreat if possible. In every moment you have a memory, know that it is a memory, know about feelings which are coming up and so on. Your mind is in the habit of believing the images, but in fact what you see is just mental noise. Maybe you had past lives like that, but it does not matter (I bet you think it does matter; that's exactly the power these images have over you). The training in returning back to the present moment (by acknowledging whatever is happening and letting it go, time and again) will gradually break the attachment of mind to those images, so you will be able to stay more stable even if these images come.

Whatever in the mind is not a hindrance to be present, if seen clearly for what it is (body sensation, feeling, mind, mind object -- technically speaking); present cannot be destroyed but we are sometimes unable to tune in back to it, and that's why we train.

As a side note: if your condition is psychiatric (you are not able to take care of yourself in regular matters, often can't distinguish hallucinations from reality etc), do seek proper treatment first.