Charity events - a challenge?

We are all asked at various times to sponsor people who are doing events for charity. But what bugs me is when the event is dead easy and really not a challenge.

I'm thinking for example - walking a mile (by someone who is fit and healthy), sliding down a zip wire (something that kids do for fun), a parachute jump (basically, you are paying for them to have fun).......etc.

I think the event should be something that is going to stretch you, that there is a possiblility that you might not achieve it......

What do you think?