I like being healthy, active and strong. I like being fairly slim without excessive body fat to make life more effort and tire my joints out. My BMI is 24 and 23 is my realistic aspirational place.
In my early adult years it was naturally around 20-21 and I was happy and well on that. With age, having had babies, gaining muscle mass and a natural bit of rounding out, my happy zone has gone up. I have no desire to replicate the build I had 20 years ago and go through a lot of sacrifice to attempt it.
It's not just BMI I pay attention to, I look at the big picture of how I feel, sports watch stats, what my body does, how clothes fit, tape measure. I just check in with myself every now and then and consider if there are habits that need tweaking before bigger issues develop. It's about how I feel rather than numbers for numbers sake.
As I get older, that happy zone may well adjust upwards again.
Age matters with BMI. We naturally gradually gain weight as we get older and while obesity is a health problem, having some reserves of body fat can be beneficial as we move into older age. Neither extreme is good, especially if muscle mass is poor.
I enjoy my food, I enjoy my activity levels. I enjoy being in my healthy female body and I balance looking after it with enjoying life. I've never wanted to look "thin" for the sake of it.