I faced this problem a couple of years ago, having realised I had lots of tools I no longer or haven't ever used. I just sorted them out and put them on ebay over a period. Figuring I didn't need and wouldn't miss them I decided to make it a project and sell them in aid of charity - Ovarian Cancer Action . This certainly helped with the motivation to do it - over several months- and I made the purpose explicit in the listings. Raised about £1500 which pleased me and the charity, and I haven't missed any of the tools.
Jim