I love the comments of people here. The nice thing about being retired is that you get to define it anyway you want
What's my top retirement insight? I don't know if I have a top insight, but I'd say whatever I'm doing at the moment is the most important thing I can do for myself or for others.
You can actually enjoy just moving whether it's riding a bike, hiking at Koko Head in the middle of a heavy rain, washing the dishes or cooking for the wife. When you move, all those happy hormones moves with you. Smell the roses. Stop and look at the mountains, the beaches and the sky. I wish I had a painter's sight. When he looks out to the distant mountain and sky, he sees things differently every day just like a two year old. How it must be so awesome. Visit the grand-kids. Be creative and laugh with them. It's easy to make them smile and you'll learn a lot from them. The older I get, the more I want what the little ones have--a sense of wonder about the things around them.
Solve the world's problem with your older retired neighbors. They are a gem of wisdom when you share your problems with them. Help someone who can't do things unless you're there. Buy lunch for someone who can't afford it. Laugh and find things to laugh at or with. You cannot take life too seriously. Be brave and learn to forgive so you can laugh again and again. Value the present. It's a gift after all. Look forward to every day. Find your small group to keep you sane and accountable. Rest, anytime you want. Explore with your sight, smell and your mind. Do not take the same road you've always taken. Take the scenic route. Widen your interest. Learn a new trick. Definitely take time to enjoy what you have been given. Don't be jealous of what others have. Some people can't enjoy what they have and they have a lot more than you. The trick is to enjoy and be grateful for what you have. Play those music that makes you happy over and over again.
It's your book and you're the author. The pages are empty. Let your imagination splash across the pages. You'll find that you are an awesome writer.