I waited 2 years beyond "retiring" age and then decided that between DH's health, expected DGC 1 and the fact that I had fallen out of love with the system - it was time to go. Juggling the family and the job came to a head one half term when on Monday DD2 was knocked off her bike at Elephant and Castle, on Tuesday Grace diagnosed with an eye disease, Wed DH admitted to Royal Free in London ,Thursday DD1 (28 weeks pregnant) had suspected DVT and was being seen at Selly Oak hospital and on Friday I was due to take an exchange party to Germany for the week and there was no one else who could go in my place. It all turned out OK, DD2 not injured, kennels happy to administer eye drops to Grace, DH not in danger and "safe" in hospital for a week and not DVT. However it was a wake-up call.
I think it is one of those things that you know for yourself.