Many people enjoy a game of croquet in their back gardens.
It is an ideal way to spend a summer's afternoon. It provides some gentle exercise without being too strenuous, it is suitable for all ages, it involves a combination of mental and physical skills, and it is possible to socialise at the same time as you are playing (unless of course you are getting very serious about it!).
Recommended Rules can be found on the UK Croquet Association Website. The Official Rules of Garden Croquet
Equipment can be purchased easily on-line, in many sports or games shops, or often from your National Governing Body.