Bhagwan,
I had the same issue when I started Barres. They're just not something your body wants to do naturally. I remember watching other people do them, and it seemed so simple and they rang so clear, but mine sounded like I was playing them with my face and afterword it felt like I slammed my hand in a drawer.
DISCLAIMER: I am in no way, shape, or form an expert on anything, as I'm still learning myself, this is just how I personally approached it.
The thing that helped me the most was breaking them down, taking my time, and taking alot of breaks. What I mean by breaking them down is concentrate on one part of them at a time. Start with JUST a barre without a chord shape and work on getting the strings to ring. Doing this let me realize what part of my finger was pushing on each string, which parts were muting strings and why, and allowed me to adjust my point finger positioning to compensate. I found that the one spot on the fleshy part of my finger closest to my hand was just too soft to get a note to ring true, but if i rotated it slightly toward the headstock, it was infinitely easier to fret, it was more comfortable for me (Your physiology may vary) and fixed my problem. When I was trying to play a full chord, I was concentrating too much on what the rest of my hand was doing, and never would have solved it. (Just make sure you don't get in the habit of backing up your pointer with your freed up fingers, it's a habit that's a headache to break)
Another thing to remember is that you are working muscles in your hand that you probably never knew existed. Like exercising anything you've neglected for any length of time, the first few times you work them, they will hate you for it :). The pain will eventually cease. with practice they will come naturally, and the force you exert to play them will seem relatively light. For as much as I use to hate the very thought of trying to play barre chords, they are now easier for me than open chords, and I find myself playing them almost exclusively when jamming with friends etc.
Just don't let them frustrate you too much. Believe me, if I can play them, I'm convinced anyone can :D (And forgive the wall of text. I tend to ramble a bit)
