Today is my 3rd try at this help on keeping motivated needed badly!

This is my 3rd attempt at this the longest try was 3 days I really would like to complete 21 days but can't seem to get past 3 days.I dont mind the taste and can even handle the swf I just can't get my brain to go along with this process and quit telling me I have to eat the sad thing is I am not even really hungry!I am overweight and have ms,fibromyalgia and osteoarthritis all at age 26 so I am doing this for mant reasons weight and health.Any tips on how to get through the day would be great night is the worst for me.Thanks Again