Hi,
Well I took the plunge and decided to book a JY holiday last year (aged 52) after losing my partner and loved it so did another later in the year. Already looking forward to 2 holidays I've booked so far this year (April and June) so I obviously speak highly of JY.
To be honest I have travelled totally solo in the past and will also do that sometimes but to go with a group of like minded singles is great. You certainly will make friends.
I think 52 is a good age you will find younger and older, my experience so far is ladies ages vary from late 20's to 70's while men 40's to 70's. The majority however are likely to be 50's & 60's and ladies will probably outnumber men, everyone gets on really well, not surprising as we are all there for the same reason "a good holiday".
Whatever holiday you chose its very unlikely you'll be the only fit timer, you are likely to find a good mix of regulars and beginers.
Mick
Everyone