Which I do - both a blessing and a curse!*snip*
Retiring early is a lot easier if you don't have kids or aren't hung up on their place of education.
Why is it a challenge and are there ways you can speed it up?
I stopped working at 36yo but still had debt to service which ate into my cashflow and lifestyle so I made the decision to sell a flagship IP and pay off all my debt. This allowed me to live off the rent from the remaining 3 IP's. It's always tough to sell an IP but if it benefits you then you have to remind yourself this is the reason why you're investing. Remember the end game which will help you focus on where you want to go.
THIS! (Except the living off rent part - wouldn't quite be there.) And would only pay off the PPOR debt, which would still be a great place to be.