It wasn't so much my retirement in late 2008 which changed my hobbies and activities list. It was switching from working full-time to part-time in 2001 which had a bigger change. Switching to part-time freed up some weekday evenings to do things in the evening as well as freeing up some weekdays to do some more daytime stuff.
When I made the big switch in 2001, I already had 2 items planned to start doing. One was resurrecting my long-dormant square dancing hobby, something I hadn't done since 1988 because I was too worm out after a full day at work. That began with one night a week but grew to 2 nights in 2002.
The other activity was a new one, my participation as a volunteer in the local school Scrabble program with several area schools. It began with one but grew to two in 2002.
In 2005, I resurrected another long-dormant hobby, playing Strat-O-Matic baseball. My collection of teams, mostly from the 1970s and 1980s when I played the game a lot as a teenager and in my 20s, was safely stored in some boxes in my closet. I also joined a message board like this one but made up of my fellow gamers from all over North America. Over the years, I have expanded my collection and filled in the many gaps in it, from missing players to teams to complete seasons.
Also in 2005, I began getting involved with my co-op's annual meeting, mainly its election of the Board as well as determining a quorum. Using my spreadsheet skills, I greatly automated a process which was slow and often chaotic.
When I retired in 2008, I was able to expand my square dancing to include a third night now that I had no more conflicts with even part-time work. That went back to 2 nights in 2014 when I became disenchanted with one dance club and had become a little overextended on my weeknights. Sadly, the caller of my remaining 2 nights passed away in 2018 and I haven't had any real desire to dance any more.
But before that caller passed away, he began teaching a square dance class at a local college. In 2003, just after I began working part-time, I began helping the caller at his class. I only had time for 1 day a week because I had to fit it in with my part-time work schedule and my school Scrabble which was often at the same time. Once I retired, those conflicts disappeared, so I was able to help out at the dance class both days a week until the college stopped offering it in 2012. But it was nice while it lasted.
After not playing the piano since 2004 and not playing it regularly since the 1990s, I dusted it off, tuned it up, and began playing some of my songs back in late 2018 after the square dancing ended. Once I got the songs (6 of my favorite Scott Joplin piano rags) up to speed, I eased back on my playing frequency, just enough to keep my skills at a respectable level.