The only "fear" I have is that my insomnia will return at some point. I have had such a long history of severe insomnia, initially caused by menopause, and then by a dependency on and a long taper from diazepam, that I have a genuine fear of it returning at some point which is why I'm really scared of ever coming off HRT. My doctor has said that it is a form of PTSD because my experiences were so traumatic for about 4-5 years.
It's not really a fear, but I am concerned about getting osteoporosis (I already have osteopenia) and dementia, because my parents had both. So hence another reason to stay on HRT.
Generally though I'm not the worrying kind. You have to make the best of every day and try to have a positive outlook on life, otherwise you might as well give up now.