I think you can find yourself by being alone (not lonely), too. When I retired, I had been told by retired colleagues that I would get bored, be lonely, need a hobby, purpose, other work, studying. None of the above has happened in 3.1/2 years, although I don't rule it out. I got myself a puppy, socialised with friends, did more gardening and cooking from scratch, read lots, and generally enjoy my own company much of the time. My children have had babies, so the family has grown, and I can flit from one to the other, have fun and then come home to my sanctuary. They descend on me for big family meals, and occasionally treat me to the theatre or restaurants, but I don't depend on them and the slower pace I have adopted suits me just fine.
I think the key is in adjusting to this stage of your life, learning to be content, and taking opportunities to do things that interest you.