I think the receipts need to be kept for seven years. I'd call the IRS early in the morning and ask. They're less swamped with telephone calls then, and they'd probably be glad to get a simple spring cleaning question instead of a complicated income tax one.
Whatever you do, focus on the immediate small task you've chosen, not the Big Picture. The thought alone of that overwhelms me at my house. Right now, I'm spring cleaning my bedroom. After I grab some cd's and get my miserable tail into the bedroom, the first thing I do is make sure the bed is made. This keeps crud off the sheets, and gives the impression of a large clean space. Then I take all the clothes etc. that have somehow piled up at the foot of the bed, and I sort them, put them away, and deal with the various and sundry other stuff. Then I do the floor on the right side of the bed..you get the idea. Over the years I've boxed up clutter and labeled it DWIL (Deal With It Later), and now I'm paying for it. I have found that I can comfortably go through a box in the time it takes to watch a movie on television. James Bond movies are the best. You watch the splashy beginning. When things get boring/stupid in the flick, you sort stuff. When sorting starts to turn your brain to lint, there's usually a spiffy chase scene or something. and so on.
It helps me to have an idea where to get rid of stuff. Clothes to charity, paper to recycling or fireplace, books and records to the Mudcat Auction *g*. It is a grand feeling to fill the ol' minivan with sacks of clothes, etc. and deliver the goods to somebody who can use it. It even feels better than the clean room.