It always amazes me that the process of personal growth never stops. Perhaps there is the pre-requisite that you must allow it to happen, even if that means deliberately stepping out off your comfort zone.
Looking back, now just in my 70s, I can recognise small life transitions that have occurred about every ten years or so. But in a general sense I know that I have to date lived through three distinct phases in my life and just recently have entered my 4th one. Will this be the final one ? Probably, but one never knows.

I imagine that every one can experience these phases in their life provided one's awareness is open to it. I am a very emotional person easily stirred, especially where it concerns my freedom or my feelings. So be aware that I may have experienced the various phase transitions perhaps stronger than a more evenly balanced person would. Timing of the phase transitions too may of course vary from person to person.
The four life phases as I see them are :

1. Physical Growth Phase : from age 0 - 20 years
   A period of physical and mental growth of the body.
   A new human being is being formed.
   We are child selfish and have emotionally erratic mood swings, crying, burst of anger, etc.
   
   
2. Reproduction Phase : age 20 to early 40s
   You find a serious girl- (or boy-) friend, get married, have children and look after them.
   You are still selfish but not just for yourself but for the wider circle of your family.
   Partly from necessity you are very materialistic during this period.
   Emotionally you have stabilised somewhat and have become idealistic, polarised, black versus white.
   
   
3. Creative Phase : from early 40s to 70 years
   This phase can start, like in my own case, with a Big Bang, the mid life crisis. The materialistic and reproductive phase is over, what the hell do I do now ?
   A time of self discovery and self expressions begins, and you become creative usually in a form of art
   Emotionally you shed your idealistic ways, you have learned and observed and have become pragmatic
   Selfishness too has (hopefully) reduced, you focus more on giving, contributing to others.
   
   
4. Reflective Phase : from age 70 years
   Upon entering your 70s something definitely changes, for you can suddenly see in the distance the exit door from life. How far away is it ? You don't know, but it is bloody well there somewhere !
   At this stage you probably know yourself pretty well. I for one am content with my past life. Looking back on it, I see it as a colourful Impressionist painting with which I am well pleased.
   
   So what is up next ? I find I focus more on the world and Universe around me, to understand and appreciate what is there and how I fit in. A period of reflection, consolidation perhaps.
   Emotionally you have simmered down now to the point that you (at least at times) can be impartial and wise.
   Selfishness too has receded even further and you allow yourself to be more generous to others. You try to leave behind something of value to humanity and the world at large.

I have presented these ideas of course from a man's perspective and experiences. Women are emotionally so totally different that perhaps for them there are differences I can not perceive. So keep that in mind.
Having said that however I can clearly see that my daughter Babette now in her early 40s, has definitely entered the Creative Phase. She is a very busy woman, Vice President of an International company and in charge of two Colleges in Australia. Despite that she suddenly started last year to write novels. Every evening, after returning home from a long day at work, she is at her writing desk, often writing until deep into the night. It is good to see.

As far as my belief is concerned I was a Christian of sorts in my Growth Phase, but then quickly moved away from a traditional religion to a vague believe in a God and a hereafter. This gradually and almost subconsciously changed into finding myself an agnostic. This was perhaps the case because in my Creative Phase the focus was very much on myself.   But then, suddenly on entering the Reflective Phase I became a convinced atheist almost overnight.