I've been retired almost 15 years, and haven't had any problem keeping myself busy. I do a lot of reading. I usually have 4 paperback/hardcover books going at a time, and spend at least 4 hours a day reading them. I also read a book on my Kindle before I go to sleep each night. Because I worked the 3-11 shift for several years, I usually don't go to bed until 3 a.m., then get up between 9-10 a.m. Besides following FR throughout the day, I do jigsaws, and other puzzles online. I watch a lot of TV shows/movies on my DVR, use Netflix, both streaming and DVDs. Because I enjoy history, I also watch a lot of British programming that I download from UK websites I've joined. They have great historical documentaries and crime/mystery programs. I visit family and friends occasionally, meet a co-worker and her husband once a month at the local casino near me, have doctor appointments, and go grocery shopping regularly. I cook for myself every day too.
One thing you'll find out after you retire is that time seems to go by a lot faster than it did when you were working.