Usually spontaneously. Oh yes, one clarification. Past lives rarely, if ever, come to you in a fashion you are expecting. That's part of the lesson.

Be prepared for the unexpected. You weren't then who and what you are today. We all have been both genders, male and female. And we all have lived in an amazingly diverse sets of circumstances in various lives, and usually over epochs of time.

There is a Zen quality, often enough, in connecting with a past life, wherein a seemingly innocuous everyday event triggers the memory to the surface. Often it's a brief flash, but sometimes there is a more extended awareness.

But one thing is for sure, the ego personality you have in your current life is not what you had then. You were a very different person then compared with today. In most cases, that's a great blessing.

Some individuals, who have had many years of disciplined meditative training, can access past lives using their training. Several of the Eastern meditative techniques, including yoga, have this as a by-product of advanced practice. All of them, however, caution quite correctly that there is a great danger of being side-tracked by past lives and forgetting the importance of living your current life.

Westerners, whose cultural programming of instant gratification often clouds their better spiritual judgement, will sometimes seek out past life regression therapy. Recreational regressions are generally silly and offer little constructive content, and can be downright dangerous if the client is suddenly thrown into a traumatic past life by a practitioner who doesn't know what s/he is doing.

If a legitimate therapist with extensive training and experience in the field suggests it to you, they will discuss your situation with you at length outlining the valid therapeutic reasons for this approach. Other than that, save your money and work on your present life. You will achieve far more spiritually.

There is no set number. You can have as many or as few as you wish. Your free choice. If you're this far into this website, you've likely had dozens if not more. While there is not a set number of lives, hundreds if not more lives are common in a cycle of incarnations.

Remember that everything which you have ever wanted to be you will be at some point in some life. Everything which you have ever wanted to do you will have the opportunity to do some point in some life. And everything which you have ever wanted to have you will have at some point in some life.

It's not until you have seen it all, done it all, and had it all, and been everything that you could be, that your cycle of incarnations winds down. How much do you desire in the material plane? That's how many lifetimes you will have.

There is no set period of time between lives. While the soul is on the metaphysical plane doing its work between earthly lives, the soul is in a dimension where time and space do not exist. My experience with clients is that the time on planet Earth between incarnations can vary from a few days, to a few weeks, to a few months, to a few years, to a few decades, and sometimes even to a few centuries.

It makes no difference to the soul what the time frame is on Earth because the soul has no experience of time on the metaphysical plane while the soul is between incarnations. Time only exists on the material plane. All the soul experiences is a simple continuum of existence into and out of time from one incarnation to the next.

Volumes have been written on this in the Sanskrit literature, and at the risk of offending the pundits, I will greatly over-simplify. Free choice exists on the other side while a soul is between incarnations. The soul has two major choices, loosely speaking.

Firstly, it could party, party, party in heaven until it uses up its good works and then must return to Earth pretty much in the same sort of place as it was in during its most recent life.

The second option may be loosely called the educational option where the soul may choose to learn lots of good spiritual lessons in a blissed-out metaphysical environment and then return to planet Earth several rungs up on the ladder.

The soul, remember, is in a state of existence where time does not exist while all this is going on. One rule of thumb is that whatever the soul expects the "other side" to be is what that "reality" is. Many traditions speak extensively on the soul's projection of metaphysical reality as the basis for between-life experience.

So be careful about what you either consciously or unconsciously expect the hereafter to be, because that's what you'll get.

Again, the free choice the soul exercises on the other side plays a big role in this, and again I will sketch this out in crude but understandable terms. The souls which take the educational option get a lot more say in their next life than the party animals. The party animals get another incarnation where they can again have a life where they play the spiritual equivalent of "pin the tail on the donkey" in the material world (sound like anybody you've met recently?).

The educational option souls spend a great amount of energy focusing on lessons learned and lessons to be learned. The general pattern here is for the soul to set up a new incarnation where a more sophisticated amount of free choice can be exercised than the previous incarnation. This includes choice of parents, ego personality, gender, physical locality, and life options.

That last one, life options, can be a bit tricky to understand, for it covers a wide range of possibilities. It could entail a specific dharmic path (a specific career and/or relationship of some sort, for instance) or it could entail an open-ended path where the taking of the journey is more important than the destination at the end of the journey. Regardless, it is free choice whose consequences are carried into material world incarnation.

One common option I see often in my clients is a soul which has chosen on the other side prior to incarnation to have a life which involves the exercise of free choice at strategic times in the lifetime. The lesson for such individuals is that free choice has consequences, regardless of whether the free choice is exercised in the metaphysical plane or the material plane, and the consequences can follow the soul across the bridge from one plane to the next.