The past – what if it’s not an event?

Hi, I think I posted a question about this earlier, but because it wasn’t answered, I may not have pressed submit. My question was about the July month of letting go of the past, which is very relevant to me. With the weekly homework to choose an event about the past and work through it, what if my past thinking isn’t really an “event” but a belief based on past experience. For instance, I can”t lose weight. That’s been around for 20 years, but is not really an event. Hope this makes sense. Must it be an event – like the example given of my mother told me at aged 6 to lose weight – or can it be around a negative belief based on many failed diets etc? thanks again.