Slowly, slowly: two weeks to Everest Base Camp

In Sherpa we say bistarai, bistarai: slowly, slowly. I say it to every group on the first morning in Lukla, and by the second week they are saying it to each other. On the trail to Everest Base Camp, slow is not a weakness. It is the whole plan.

Days one to four: into the Khumbu

The walk begins gently, along the milky Dudh Koshi river, over suspension bridges heavy with prayer flags. Porters overtake us with impossible loads, and yaks have right of way. The climb to Namche Bazaar is the first real test, and the first view of Everest, a dark pyramid with a plume of snow, appears through the pines.

In Namche we stop for a full day. People always want to push on. I take them up to the ridge above the town instead, and we come back down to sleep. Climb high, sleep low: it is the oldest rule of altitude.

Days five to nine: above the trees

At Tengboche the monks chant at dusk, and we sit at the back of the monastery with cups of butter tea. Above Pangboche the trees end and the valley opens into high pasture, with Ama Dablam watching over everything.

• Drink four litres of water a day, more than feels normal
• Walk at a pace where you can still talk in full sentences
• Say how you feel at breakfast, honestly, every day
• Eat the dal bhat, even when you are not hungry

Every morning and evening I check everyone's oxygen level with a small clip on the finger. Numbers drop as we climb, and that is normal. What matters is how people feel, and whether it gets better after a night's rest.

Day nine: Base Camp

The final walk from Gorak Shep follows the moraine beside the Khumbu Glacier, a frozen river of grey and blue. Base Camp itself is a jumble of rock and ice, and there is a painted stone where everybody takes a photograph. Last season a retired teacher from Leeds stood there and cried, and then the whole group did.

Why slow wins

The groups that rush have headaches by Lobuche. The groups that go slowly are the ones still smiling on Kala Patthar at sunrise, with Everest lit up gold in front of them. Bistarai, bistarai. It works every time.