Just that really! I'm in my mid 30s and the past 5 years or so have gone SO fast.
I was thinking the other day about how many key life events happened in my 20s versus only two in my 30s (birth of my youngest when I was 30 & a significant bereavement last year) and maybe that has something to do with it? (See also en.m.wikipedia.org/wiki/Reminiscence_bump ) I've tried to keep doing some new things every year but with young children it's really just been things like going in holiday to new locations, not the big events like getting married, graduating university or buying a house!
Is this as fast as it's going to feel, or does it keep getting faster and faster and I'm already further through life (as it feels to live it, if not in years) than I realised? 😨