THURSDAY Our first proper walk is a gentle "stroll", but the altitude means we have to stop every 10 minutes - even the fittest throws up by the path.
I'm spurred on by memories of last month's National Association of Head Teachers' annual conference dinner in York, where delegates donated more than pound;1,700.
FRIDAY We walk for 11 to 12 hours, climbing to 4,444m along paths barely big enough for two boot-clad feet. It's a challenge - physically, mentally and emotionally. I burst into tears at the top.
saturday Some coloured pencils I brought are given to local children before we leave camp. Toffee, a teddy bear sponsored by Cheshire's Childer Thornton pupils, attracts heaps of attention. We then face a six-hour walk, often in torrential rain.
SUNDAY An easy day. Three hours' walking through desert-like terrain.
MONDAY Supposedly our second hardest day, walking the Inca Trail to Machu Picchu. But striking teachers have blocked trains from Cusco and we wait in vain for two hours for transport. We are forced to forget the walk: it's disappointing that our first view of the lost city of the Incas is from a bus.
TUESDAY Back to Cusco, where the streets are lined with armed police. We are higher again and breathless, even before running from a tear gas attack. The trek has been fantastic. The best thing I'll do in my life, and the hardest.
Clare Dean is deputy news editor of The TES. Her 10-day trek to Peru for Cancer Research UK (see Friday magazine, May 2) has raised more than pound;13,000. If you would like to donate, contact firstname.lastname@example.org