Creating my own shadow

Why is it that I am never satisfied with my own personal  accomplishments in life? I am never happy enough to turn around and pat my own self on the back and say good job. I am forever looking at someone else and saying "They are so much better at (fill in the blank) than I am. Too bad I can't be like them. Maybe my life would not be like it is now."

This happens every now and again and frankly I am started to get irked that my brain continues to do crap like this. There are so many who would trade lives with me in heart beat. They would not understand what it is that I could possibly not be pleased with. I am one of the few who have actually accomplished something that I have dreamed about doing my entire life. And I treat that accomplishment with such flippant dismissal as if it didn't take everything I had to see it come to fruition. Why? I just can't understand why I can't be happy for myself.

I'm not whining or feeling sorry for myself. I just want to understand why my brain is constantly working over time to inform me of every fallacy I have, and making up some that I don't, and puts them on replay all the time. It wasn't always like this for me. So why this constant berating, even after I have done so much and endured so much? When am I going to be proud of where I am and happy that I progressed to that point?

I never feel jealous about the others I'm always comparing myself to. I just always feel less. Like everyone is pulling out a measuring stick and I never seem to make it to the point everyone else is reaching. It is probably the indirect reason I stay to myself. Everyone around me seems to be progressing by leaps and bounds and I feel so inadequate. But why? I have proven that I'm not. Others can see it. I know people think highly of me; my peers, my professors, they all believe that I am this stellar person. So why do I think differently? In direct opposition. As if they are all lying to me.

I honestly have no idea why this keeps happening. And I have lived with it for so long, I almost accepted that it was just the way I was hard wired. I almost accepted the constant internal second guessing of what everyone else accepts as truth. But honestly, I am tired of it. I despise the feeling. I don't want to feel judged when the only one who is doing the judging is me. I am ready to let go of this thing, whatever it is, and live my life out differently. I just want to be proud of myself.