I know I'm a little late to this post, but a few years ago I did a 50 things in my 50th year book. I used a 10x10 80 page spiral bound sketchbook. This allowed for some 2 page spreads or just one page layouts. Near the bottom of every page I added a black strip of paper. Below it I marked the date and in pencil any notes I might need before I finished the page. I kept ephemera and a photo, if I had one, paperclipped to the pages and recorded events through the whole year. It included things like a screen shot of my computer desktop on my birthday, I received a box of sweets from a friend, a day spent with my dearest friend, the AA Rejects concert I went to with my daughter, a Girl Scout event or two, the my daughter's first time voting, several trips to Disney, the day we watched indoor surfing. At Passover, I brought my book, explained what I was doing and asked everyone at the table to sign it. Whatever, it did not matter what it was that we did, just that I recorded it in the book. I never kept count of the things I did, just kept putting stuff in. In the end I have a few more than 50, but I'm OK with that. I was all about the journey.
Now I'm ready to do a 21 new things for my daughter's 21st birthday.