I'm learning to play the guitar. It's challenging, rewarding, fills in lots of spare time and best of all it doesn't cost a penny once you've got an instrument.
If you want to do more flying, try this:
1: Get the wife and kids out of the house
2: Make yourself a cuppa
3: Get out your guitar
4: Settle into your favourite comfy part of the house
5: Play the first note of absolutely any song you like - It really doesn't matter because I can guarantee that now the company will ring calling you out from standby.