My grandmother is turning 90 shortly and she has asked that instead of gifts we donate to a specific cancer charity as she has this kind of cancer. I am going to donate as much as I can but my grandmother is loved by many of my friends and when I have said to anyone (she only asked this of family or anyone asking what she wants as a gift) they have also wanted to donate. This gave me the idea to do some kind of fundraiser to raise as much for the charity as I am able to, however I can't quite think what to do. I am trying to think of ideas centering around '90', had thought 90 miles in 90 days but my DH pointed out that I easily already do this anyway just walking. I would quite like something fitness related, something that is a realistic challenge (I have 2 children under 2 plus a 7 and 12 year old at home and DH works away a lot). I had wondered about walking 90 miles, cycling 90 miles and swimming 90 pool lengths but wondering if anyone might have any better ideas?