I just did my first solo trip 2 wks ago. Something I had to keep reminding myself was "it's just you". You don't have to appease your group when making decisions. So, if a ride is 85 minutes, waiting by yourself is a lot easier than with a party of 4. Another item I found useful was when you get close to the front of the line make sure to let the cast members know you are a single rider. For several rides when I told them that I moved past a lot people to fill in when a ride wasn't full.
Also, with some restaurants I found they were able to fulfill my requests as a party of 1. Meaning if I wanted to sit by a window or in a certain location it was easier to do b/c it was just me.
If you start feeling lonely, depending on where you are staying, I spoke with the concierge to let them know I was solo and some other guests had done the same. We were able to meet up for drinks, park days, or ride shares.