It brings out the possibilities you could have had. The pain of the fact that you never had. What life could have been, should have been. It brings back hurt, pain and regret. Why didn't you do that? Why did you listen to everyone? Why? Ironic, because no body can take responsibility for what went wrong in your life. And no one else has the answers. Generally, the answers to all the "whys" is because you were scared.
Sometimes, it brings back the hope, makes you realize the fact, that you're lucky not making a few decisions you could have made. And a consolation, that may be, just may be life isn't so bad anyways. It makes you proud of yourself. And you pat yourself, saying "Good Job!!".
But the sun never rises on the horizon of "if". It's all but past. It's funny, how much regret makes up a huge part of our lives. We never give up the pretense of happiness, even though, we've made decisions which makes us responsible for some of the worst mistakes of our lives. Some which can ruin everything. We run from it, trying never to think about them. We tell ourselves, "We're but human." Though we aren't convinced about it ourselves. We learn to call it "experience".
Some moments can change our lives, turning it away from the course. We can never be sure for our lives to go the way we've planned. I wonder, if it is choice or destiny, which plays a larger part in our lives. We can choose all we want, but still never be sure. And if what we want doesn't happen.. then, we replace the wish, with blame games and later with an "if".
As the colours of the memories fade, you settle into your regret. Something you'll live with for the rest of your life. Life would still go on, just not take the course you wanted it on. The consolation we give ourselves, when what we've wanted doesn't happen, learning it from the last generation- "What ever happens, happens for the good", "God has emptied your hand for something better" etc. Only feels like a consolation, doesn't it?