How can I get back to losing weight?

I would love to get back to losing weight. I sit home and think today is the day to start. But I ask why do I do this to myself. Why do I put myself down when I can not get back on track. I put myself down because I screwed up. It seems like I beat myself up for everything. Why can I just put positive thoughts in my mind. I can see the end results and the light at the end of the tunnel. But there I go pulling myself back because of the negative thoughts in my mind. I need to over come those thoughts to get going down the tunnel to the light. I am hoping to get support from my friend on here and family to get moving. I know with Gods help and my friends and family I will get the motivated.