Struggling with weight and health issues

I am 54 years old. I am 100 lbs overweight. I have been dieting since I had children 31 years ago. The liquid diet works for me but I quickly gain the weight back. I know this is not the answer for me. I have arthritis in my right knee and leg. Exercise right now is hard. I have tried walking but cant for long periods. I am killing myself and I know it. I have hypertension, diabetes, acid reflux disease. I am tired of feeling sorry for myself. I pray constantly but I know I need to do more than pray. Can you give me any guidance on how to proceed? My last 30 day fast was done in April. I am retired and don't have much money. If you could please show me an economical way out of this weight struggle I have been going through most of my life I would greatly appreciate it.