There is a charitable organization that picks up donations in my neighborhood, called Viet Nam Vets of America. I have them come to my house once per month throughout the year. Knowing that they are coming motivates me to go through my closets and shelves to get rid of items I no longer need. Since I want to make it worth their while, I try to get at least 3 bags of items to donate to the VVA. It feels great to get rid of things regularly. The VVA leave me with a large yellow bag for my next collection day, and a receipt for taxes. I also have loved books about decluttering your house/life such as Better Than Before by Gretchen Rubin, and of course Marie Kondo's book.