jaideepv, here is some practical advice to complement the spiritual advice:
You probably have a belief that change is difficult. Change is not difficult, it is very very easy...as long as you only try to change a little at a time. If you try to make sweeping changes you will encounter all kinds of resistance and find yourself without the motivation to act.
The easiest way to change is to make a small change and then, over time, make it bigger. If you want to exercise more, start by taking a five minute walk every day. If you miss a day, don't beat yourself up, just take a walk the next day. After doing this for a few days, walk a little farther. If taking a fifteen minute walk every day is too inconvenient, break it up into a half hour walk every other day. The point when you're starting out is not to lose weight, it's to create a habit that can be built on.
Once you've been walking every day for a few days or weeks, maybe try doing some other exercises, like a push up every day, or a couple of sit-ups. Just make a very, very small change. A change that is so small you barely even notice it. Over time, these actions will become habits and you will just do them. Every once in a while, increase the amount of effort you are expending just a little and try to build that into your routine. Maybe add a fifteen minute bike-ride every week. Gradually, little by little, you will start to feel better about yourself and start seeing yourself as an active and healthy person. When your self-image begins to change, you will find it much easier to make the changes you want.
This technique can be applied anywhere in life and, as long as you actually want what you think you want, it will be effective. You can apply it to your diet by substituting one healthy meal every week for an unhealthy one. Dieting is hard because people run into the wall of ingrained habits and self-image. You have to change yourself slowly, the way a turtle walks. Don't try to completely change your diet all at once, just change it little by little. Give yourself time to adjust to finding new foods, finding recipes that you like, enjoying the new foods that you're eating. If you try to cut out everything you are used to and like, you will resent the diet instead of appreciating it. After eating a healthy meal once a week for a couple of months, increase it to two healthy meals. The goal is to create a permanent change in your habits so that dieting isn't a challenge, but a gradual reorientation of your thoughts and actions.
The only way to prove to yourself that this works is to try it. It is the easiest thing you will ever do.