It’s not just a Bobby McFerrin song, it’s a lifestyle. Being happy is a decision you make about how you want to live and you get to make this decision each and every day. Being happy is attractive and will attract other happy people — and that includes singles attracting prospects.
Being happy in your life right now, being happy being alone and being single (not the same thing), is attractive. People who let their current situation get the best of them can come across as pessimistic, bitter, and negative on a date which is obviously a huge turn-off. People like this seem to depend on finding on a mate in order to make them happy, but your happiness should not be dependent upon someone else. It sounds logical reading it, but for some reason people don’t always identify as one these people or understand how to change it.
You want to be someone who has made the best of their situation by enjoying their life as-is. You’re single? So what! Find joy in all of the amazing things you have going on in your life, not what you’re missing. That said, make sure you do leave room for that special someone!