To see or not to see... that is the question

We look at things all the time but do we actually see? Consider the fact that at least once in your life you have probably noticed something different or new after encountering the same walk/bus ride/classroom/office/etc day after day. It was always there, you just happened to now notice it. It is not the 'thing' that is different, but it is you that has changed.

How many people could we have really connected with do we scurry past without noticing, how many experiences should we have had but we were too preoccupied with ourselves, how many shooting stars/rainbows/utterly breathtaking sunrise/sets do we miss because we couldn't be bothered to look up?

This point has been driven home on different occasions in my life. As my previous partner and I explored each other's lives early on in our relationship, I discovered that he lived around the corner from where I was taken to a football match as a date with another guy in 2003. In fact, I could have walked right past him only to meet him a few years later and then end up with him for another 4.5 years.

I guess I am wondering about the people we are seemingly destined to meet. If we miss the opportunity once (because we're gazing at our navel or shoes) are we given a second chance? I know for a fact I was once, but how many more opportunities pass me by because I don't see them for what they are? How does one learn to see rather than just look?