Addressing your 3 issues:
Not being able to sleep happens to me when I have a lot on my mind. For awhile my subconscious kept me awake because it didn't like the dreams I had when I fell asleep & I had to be TOTALLY exhausted befire I could sleep. That is over, but I still sleep best when totally exhausted. This is easy to have happen since I own a little farm & just get physically exhausted by the time night hits. Honestly, good physical work/workout during the day works just as well as melatonin.
Yep, I used to feel that way about getting old. All the older people around me acted & thought REALLY OLD & I wanted to be nothing like them. Ok.....I made decisions & choices throughout my life that kept me frkm ending up like them. I chose college & a career (computer engineering). The guys I worked with played racquetball at lunch every day. I played racquetball with them which kept me in good shape through my 40's. I did downhill & x-country skiing in the winter until in my 50's & dressage horse back riding. All these kept my mind & body active. Then I finally left my bad marriage & bought my little farm across the country where I knew no one & got to start life all over. Maintaining my farm, the house & equipment myself, I had to learn lots of new skills which kept my mind & body active. I still ride horses. For years when I first moved here we went trail riding on farms at least 3 days a week. Lol.....I am still (at age 67) skilled in climbing fences, moving around 50 lb bags of horse feed & large bales of hay. Seriously, I am in just as good of shape & stronger than I was when I was younger. I have had major injuries I have healed from & kept going (ACL knee reconstruction, fractured hip, neck fusion, & a compression fracture of my back). The secret of staying young mentally & physically is to keep your mind learning new things constantly & to stay in shape physically. I remember when I was young, my mom said people stop learning at a certain age. She was WRONG as she was about many things. Today I feel cheated if I don't learn something new daily. That is how we stay young into our older years. NEVER STOP LIVING & enjoying the life around you.
Your third thing is what I was talking about under #2.....enjoying life around you. My life is filled with wonderful things (& I live alone) I have wild raccoons with their babies that come begging for food. Watching the bugs, butterflies/moths & birds that frequent around my house & sing to me. Exploring around my woods & honestly, just mowing the acres of grass I maintain on my farm & at the farm where I keep my horse is enjoyable because it gives me time to relax cause I can't do anything else while doing it & the end result is so satisfying to look at. Look at things around you with fascination & excitement rather than with a CRITICAL eye & find the beauty & joy in the things you see.
All this is getting me through what I see in the world because my little world around me is beautiful & peaceful. I pay attention to everything in the world out there but my own little world is my retreat where I can regenerate myself. There are stressful things that happen around me but I have learned the skills needed for me to stay in control while working with or around them. All things we learn with age that really help us grow THROUGH the ages rather than just get old.