No it's not the One Direction song, it's about the one thing you want to do with your life, and how you treat it. When you have a lot of things you want to do with your life, you've got a ton of options, but when you solely focus on just one thing, everything else vanishes, leaving just that one thing in your head. When you only have one thing, you want to cherish it... treasure it... and give it your best.
Running is a passion of mine, and it is one of the few things that I actually do during an average day. Yesterday, I went out for a pretty fast run, running 3.96 miles in 25:25, an average of 6:24 min/mile. It was a good run and I was able to push myself really well. Running is important to me that I make sure to take care of myself. I did say that I believe wearing flip flops can help your feet get stronger, but I believe I failed to mention what wearing it too much can do. It can make the individual feel a lot of pain in the calf area. Running being an important part of my life, I treasure my feet and how I treat them, to make sure that I do.
However, once in a while, something else takes its place because I lose track of the main thing, the one thing that I want to focus on. When I lose that, I lose what is important to me. In caring for it and cherishing it, you put yourself into it, and part of you 'lives' through it. How you treat what is important to you really means a lot, because people would look at it and judge how you act and whether or not you really are working towards your goal. If you only do things half-heartedly, is your goal really that important to you? No.
If your goal is really that important to you, then what you ought to do is to give it your best, to show yourself and the people around you, how much you care about that one goal. If you don't have too many goals in your life, then that one goal becomes that much more important. It becomes the one thing that your life is about. The more choices you have, the less you'll be able to focus on improving yourself because there's just too many things going on. The less choices you have, the more focus you'll put in to the goals, which in turn will give it more power, where you'll be able to put your best into it.