Am I looking for a "reason to do" or Am I looking for a "reason not to do"???

Had to make a decision recently. There is this certain project in which I participate every year, this year also the project is happening but I had not signed up for it. The reasoning I had was that I may not be able to do justice to the project due to other commitments. I kept on postponing my registration because of this reason.
I spoke to my guide in the project and after some time of discussion (just a 4 minute telephone call), I was very sure and confident that I can take it up and execute what is expected from me.
What has shaken me up was the fact that just before I spoke to the person, I was convinced that I won't be doing the project this year. After I spoke to him, I was convinced that I will do the project this year.
What changed in the 4 minute conversation we had?
I realised that the reason for my decision was not because I had commitments or I was busy or I don't know how to plan my time or any of those reasons. But somehow I had convinced myself that I don't want to do the project this year, and because of this conviction, I was able to see all the reasons not to go ahead.
Before we spoke, I was looking for a reason for not doing the project. After I spoke, I realised the value which is added to me by the project and how I can return it, and suddenly I was looking for a reason to do the project.

One more example...
You came home, tired from a day full of office work. She said lets go for an evening walk. You said you are too tired. Walk cancelled. You received a call from a friend, he has got 2 tickets for "Fast & Furious 5", guess what, you are on your way to the movie theatre.
Keeping it short and sweet, you were looking for a reason for not going on the walk, on the other hand you were looking for a reason to go on the movie.
If you are one of those newly weds, you are probably leaving your office early these days to go on an evening walk with her... in this case, you are looking for a reason to go on a walk with her...

Same is applicable in so many aspects of our lives...

I'll keep this one short because I am still understanding the impact of this realisation...
The only rule I follow these days is that for everything I do (or I don't want to do), I ask myself one question - "Whether I'm looking for a reason to do, or am I looking for a reason not to do?"