It seems I read/hear a lot about folks downsizing to move into retirement. But, then, the issue in retirement becomes what to do with all that time. One obvious partial solution is to do volunteer work. Hopefully, enough of us retiring folks will do that, so as to make a real difference.
However, that still leaves a lot of time for other things. Personally, I like to engage in something that I can do every day, that is an endless journey on which I can improve. Music is perfect for that. For me, that is guitar and piano.
If I a collecting anything these days, it is downloaded lessons from Homespun, Guitar Workshop (Stefan Grossman's catalog), Truefire, and a few others. I don't want to get involved in things that have to cost me money every time I want to participate, such as golf. There is a lot I want to learn on both piano and guitar, and budgeting for the purchase of lessons works because once I have the lessons in hand, they no longer cost me on a continuing basis, yet I can focus on what I want, loop as often as I need to, slow it down as much as needed, etc. By purchasing this material when it is on sale, I get by fairly inexpensively.
I also have a nice collection of fakebooks, guitar books, and piano books that I have collected over the years, many no longer in print. I have heard of folks being able to sell stuff they have had for years and make big money from it, but that has not been my personal experience. I guess I just don't have anything of value in whatever market there is for this stuff. That is fine, since I am actively using the stuff anyway.
I do know some folks personally who collected certain kinds of dolls or other knickknacks, believing they would someday be worth big money, but that never materialized and selling would mean taking a rather large loss. So I am not alone in that. Fortunately, I have not collected anything for that purpose, instead acquiring for its practical value to my own interests. There has always been at least intrinsic value in that for me.
Tony