Don't be fooled by the "fill your time" idea. You will have no trouble doing so, but you will have time to take delight in what is around you and all the things you can now do that you did not have time for.
Here are some of the things that I do: I am a school governor (and hugely valued because I am the only retired person there and can step in for meetings etc. during the daytime when others are at work), I belong to a choral society (also on the committee and responsible for publicity, sponsorship, programmes, including writing the programme notes), I belong to a local book club, I run the village library,I plan and execute a huge community choirs project every 3 years, I run a singing group of my own, I look after GC 2 days a week, I go for a half hour walk/limp every day, I care for my OH who has PD, I do the garden, the shopping, the cooking etc........is that enough!? I also sit in my lovely garden with a drink and a book and enjoy the view - and I get up when I like.
I am never at a loose end, believe me; and neither will you be.