Original: While participants do need to be reasonably fit to stand a realistic chance of success in the challenge, most active people, and particularly those who are young or used to hillwalking, should not be put off by the daunting prospect of climbing three famously high mountains in succession.
Simplified: You need to be quite fit to do the challenge in 24 hours, but people who are young and active, and people who are used to hillwalking, can do it.