Wow, well this is a hard question to answer since I consider myself to be a free spirit and do not like being tied down. When I became a teenager, the only thing I thought about was boys and dating them and whatnot. Buuut! As I got older and having so many terrible relationships, I started to pull away from that mentality and enjoy being single.
There are so many perks that come with it. You can hang out with anyone you want, without worrying about getting the approval of the person you're dating. You don't have to check in with anyone or be in at a certain time because your boyfriend will be waiting on you. You can have guy friends and not worry about what your boyfriend might think, and you don't have to worry about cheating because you're not with anyone.
That's the way I used to think anyway. Recently, I've found myself wanting to find someone who could be my friend, along with being in a relationship. Even though being single can be fun, when you find the right one, it doesn't matter any more and you don't want the things you used to. I know that sounds kinda cliche.
It's not about missing the things you could do while being single, but more so about incorporating those things you enjoyed into the relationship you have.
That's just my opinion... so.
There ya go.