To get things out of the way: yes it is hard being alone. But it is also hard to be with someone and is very hard to take care of kids and family and such. And it is waaay harder to be with wrong person. There are no easy roads in life and being single is one of the easiest.
Now I’ll focus on practical advise:
- gym every day. No excuses. If you don’t know what to do or lack motivation- get a personal trainer.
- besides gym pick an active “hobby”. Cycling, rollerblading, running, skiing, surfing etc. You need self-supporting way to spend time outdoors. Again: do seek instruction.
- learn to play music. It is very healing and rewarding. Also frustrating and hard. Guess what? Take classes. Joining (community) school is great. Getting into local band is amazing. Most importantly here: you do not need to talk to these people. Same goes for drawing studio.
- professional education. Maybe you always wanted to be CPA?
- deep and challenging activities: sailing, diving, flying, mountaineering etc
- checklist reading, movie watching
- study textbooks
- systematic traveling
- volunteer
- build things with your hands and give them away
- learn to recognize your emotional state and how it changes.
My “qualifications”: I was single for ~10+10 years.
+1 for physical exercise. Curious though why you (or anybody else) would separate running and/or cycling from the gym? Gym gets its own (emphatic!) category and the sports are separate. Not a criticism, genuinely curious.
Does "single for ~10+10 years" mean 20 years, or that you were single before you were 10 and then till age 20?
Great advice, but don't treat it as a checklist. If you like to go to the gym, do it. If not don't do it, leave alone every day.
Your focus should not be in improving yourself and being the best you can be. It's about getting to know yourself better.
What is it that you enjoy. And if you don't know, now's the time to find out. Maybe it's going to the gym, maybe it's finding a great breakfast place. Sitting there, having breakfast, being around other people.
Finding activities that you enjoy doing outdoors, bonus points.
You've already done the first step in asking for advice. Even though it might sound neglectible, that's a great achievement. So many people suffer from depression and have a hard time to take this first step. Congratulations!
Get out there try things, learn who you are. Maybe there's this thing that you always wanted to do places you always wanted to see. Now is the best time to do it. And if there's no such thing, you've been given a great list of things to try.
Best luck to you in this new phase of life!