What a good idea! And, like many good ideas, it can be made even better.
Let's make geocaching compulsory - a legal requirement to find five-a-day. Have you done your five-a-day today? It's good exercise, and stimulates the mind.
Let's make programming compulsory - a legal requirement that everyone be provided with a Raspberry Pi and forced to write five programs each day. Have you written your five-a-day yet? It stretches the bain and keeps you alert.
Let's make bike riding compulsory. Everyone over the age of two should be provided with an age-appropriate bicycle (and helmet), and be required to ride five kilometers (not miles) per day. Have you ridden your five-a-day yet? It's good exercise and toughens you up each time you fall off.
Readers of this blog are invited to suggest further compulsory activities - even if all of these make it impossible to find the time to maintain their allottment.