I never make a fire when I'm alone. There's too much responsibility... I MUST put it out. If I never start it, I don't have that problem. But I sometimes carry one of those little battery tea light candles, and put it in front of me and my Helinox chair facing the water in the evening. I guess I'm easily entertained that way. They make really crummy roasted marshmallows, though.
I carry a nature guide for the region, or the park. That way, if I see an interesting bug or flower or animal, I can identify it, and learn a little about it. I've also usually traded out the guidebook for those foldable birds of ____ or flowers of ____ pamphlets. I don't usually see rare things, so a good set of pictures of common things found in the area is enough for me. I use progressive lenses, and years ago, found that if I sat on the lakeshore (I used to live and hike along Lake Superior) and read, when I looked up, I'd have to squint and strain before actually seeing. I started loading a book on an MP3, and would use one earphone. Then I could still hear the waves or birds or bears, AND have someone tell me a story. That was pretty wonderful. I had to be careful, though. I like mysteries, and sometimes when I'm in the middle of no where, reading about a serial killer, I get scared. Since I moved and do most all of my hiking in Yellowstone, I'm less inclined to listen to a book... there are real bears (I had a black bear in camp last summer) and real elk with pointy antlers and real bison (scariest thing in Yellowstone, except for rental RV's). I want to hear animals, though I'm not sure what I would do if I did have one enter camp in the middle of the night.
I am now very comfortable listening to whatever sounds float in to my campsite. It's pretty neat waking to the sound of a backcountry geyser, or a moose splashing. Except once, it wasn't a moose, it was an armada of little merganzers. The next day it was a moose!
I remember the first few times I camped alone. I was pretty sure that Bigfoot lived nearby, that rattlesnakes and copperheads were sprinkled around camp like the arms on a pinball machine, that the men at the next backcountry campsite were the killer-perverts of the Internet (mind you, they asked me if I'd like some of the filtered water they had, in case I didn't have a filter), and that a hungry bear was headed my way. Now, I rarely camp with others, and don't really like it much. I have to try to be nice, and patient, and give a little. Mostly, I couldn't care less. I don't remember the name of the poem, but it ends with "if I go to the woods with you, I must love you very much," or something similar. That poem speaks to me. I go to the woods to for so many things, and having more people usually takes away one or more of those things. There are few people I'm willing to surrender that serenity for. There are lots of times that I feel like a wimp because I don't go miles and miles into the back of beyond campsites. But I guess I don't go to be nowhere. Sometimes two miles, or less, meets my needs. Friends who don't backpack look at me kind of funny when I tell them that I only went in 2 miles. People who do outdoor adventures will hear that, and quietly nod. That's one thing that I like about this group, people converse about how they meet their own needs, whether paddling or cooking or sitting around a fire or setting up a tarp or whatever. Nobody says, "You're doing it wrong," but they do say, "I do this, and it prevents ___ or allows me to ____."
If you want to solo, you'll grow into it.