I retired at age 55. That was 11 years ago. Here are some of the things I noticed and learned.

1. Retirement is not like vacation. In retirement you have a different relationship with time. Vacations are usually time limited and you are aware of this while on vacation. The realization that you are not going back to work is something you can’t prepare for until you are retired.
2. You not only retired from something (work). You should retire to something. You have to know what you want to do with yourself and your life. No one can tell you. You would be surprised at how many people don’t know who they are or what they want to do.
3. Everyone has a bucket list of things they think they will do in retirement. In reality some of those things you will decide are unimportant. The rest you will complete in 6 months. After you’ve finished your bucket list you have to figure what to do next
4. Someone else mentioned loneliness because everyone else is working. That is true. You have to be comfortable with being alone if you retire before everyone else. You should actively plan things to do with other people.
5. Within a year you will lose touch with many of the people you worked with and saw and talked to every day.
6. Retirement doesn’t cost as much as you thought. Before you retire you should finally track your expenses and estimate future expenses. Learn how to use a spreadsheet. Track EVERYTHING for 3–4 months. Note there are 3 types of expenses. a) daily expenses b) regular yearly expenses c) unexpected expenses. Plan for an emergency fund.
7. Learn to live within your means and enjoy it
8. Your pace of life will slow down. Learn to accept it and relax a little.
9. Accept your new life. Don’t regret your past life. Don’t be embarrassed to tell others you are retired and that you are enjoying it (if you are). Others may not understand you.
10. Understand that there is both financial independence and retirement. If you are financially independent then you are totally in control of what you want to do each day. If you want to continue “working” and collect a paycheck then that is up to you. Enjoy.
11. (late addition) If you are really looking for something to do then consider volunteering. Volunteering can take many forms. There are huge number of opportunities out there. Research says that doing something for others is a powerful way to increase your own happiness.