I mean the years where you were thoroughly enjoying adult life, doing whatever you wanted (obviously within reason) with very few responsibilities. Be that travelling, having a great social life, being a cosy hermit with Netflix, focusing 100% on your career; whatever total freedom meant for you; how many years did you have before becoming parent. And what made you feel you were ready to give up those freedoms to have children?
I didn't like my university experience sadly and saw it as an extension of something to endure like school to reach a better side and it did work, but it means I count these 'great' years from after finishing university.
DH and I do want children but are enjoying life right now and want to feel we've made the most of it before we start our family. I'm not saying that having a family is not wonderful in itself; clearly it is and we do want that, I'm just very aware that it's a very different kind of wonderful and we need to be prepared to say goodbye to this part of our lives for now at least when we decide to start trying.