Help me organize my book collection?

I must literally have 1000 books. I have so many that I can't find a book when I want it. I'm trying to decide how to organize them...some are on shelves and some are in boxes. One idea is to, say number the boxes and list all the books in that box in an excel spreadsheet. The other is to just generally organize them according to category, i.e. health and fitness all together and stock market books likewise. Either way, it will be a big job. I'm open to any and all suggestions. P.S....I have Chronic Fatigue Syndrome...so physical effort is a challenge. Thanks in advance.