50/50 Question

When do I know if I should change my thought or process the feeling without changing the thought?

After hearing a coach week call, Brooke advised the woman to process sadness and that there was no thought to change.

The circumstances were a person who decided not to be vaccinated and felt isolated as she can’t join the yoga retreat she was registered to.

Brooke also adds that feelings are 50/50, but I thought that by choosing your thoughts (managing your mind), you could change the ratio to whatever you wish to, even 100%.

So, I may have missed something or mixing things. Could you please help me clarify this?