For me, after being around for 57 years, it was the teen years.
I was then too old to be bossed about and too young to be held responsible for a lot of 'things' and of course it was a time of 'firsts'
First time falling in love; first kiss; first time driving a car; first time staying over at friend's place; first time out of the country; first time handling a hunting firearm; and first look at a dynamic tension excersize being done. I am sure there were other firsts, but these came readily to my over-half-century-old brain cells.
I find that as one grows old or get on in years, one seems to develop a certain kind of cynicism i.e 'believing the worst of human nature and motives; having a sneering disbelief in e.g. selflessness of others'