I'm 51. And loving my life.
A few random thoughts:- the only negative about hitting 50 is thy at I was suddenly aware that my decades were running out. Possibly just another 2 of hopefully excellent health, but who knows. So I would have tried to make more of my 40's, although with young children that can be hard as they are all absorbing.
Be on the look out for new interests and hobbies. I haven't exercised since school and I have recently taken up running. I love it. I've always viewed gardening as nothing better than outside housework, but recently have discovered I love that too. If I had been told I would be spending huge chunks of my day gardening and running at 30, - or even 48! - I'd have laughed in your face and been incredulous. So be prepared to have a total change of heart over anything, really, and embrace things if you do find yourself doing things that were previously alien to you.
The menopause has been a doddle. I realise that it isn't for everyone, but for me it has been fine. Rarely had to think about it. Stopping periods is wonderful.
When you are in the middle of a stressful time with toddlers/babies/Young children, it is worth it. Those days do stop, although you don't believe they well, and you get teenagers who are decent people and good company at the end of it. Obviously it isn't all easy, but I'm enjoying my dc far more now than I did when I was bogged down in those never ending early years.
Try and save for a rainy day if you can. Not at the expense of family experiences though.
I'm feeling a bit more creaky, but 100% enjoying life. Don't fear getting older.