I think the secret to how to spend your free time is to not do too much.
For example, last Tuesday I had a rare free day (I was off work and the boy was at nursery). I used this opportunity to align our patio door, clean an oven tray and record a #prongcast.
It’s not for me to say if I could have been any more productive but it was certainly a relaxing day (that might have had something to do with the pint and a half I also had).