Mera Peak is not a technical climb, but at 6,476 m the summit is higher than Everest Base Camp and it is reached by a long snow plod in the cold. Altitude and cold are what turn people around here, not difficulty, so preparation is mostly about endurance and about giving your body time.
Train for four to six weeks at least
Build cardiovascular endurance with running, cycling, swimming or hill walking, add leg and core strength for carrying a pack over uneven ground, and do long hikes with the pack you will actually carry rather than an empty one. Summit day runs 10 to 12 hours and comes after two weeks of 5 to 7 hour days, so stamina counts for more than raw strength. Mental resilience counts too, because much of this climb is discomfort held for a long time.
Let the itinerary do the acclimatization
Zatrwa La at 4,610 m comes early in the trip, and the drop afterwards to Kote at 3,691 m looks like wasted altitude but is textbook climb high, sleep low. The rest day at Thangnak (4,356 m) is not optional. Khare at 5,045 m holds the last lodges, and the day there is a rope, harness, crampon and ice axe session with the climbing guides. Above Khare you are on the glacier, with base camp at around 5,350 m and high camp in tents on snow. Tell your guide about headache, nausea or fatigue, and go down rather than up if the symptoms are worse the next morning.
Get the boots and the glacier kit right
Start with the boots: insulated, rigid-soled mountaineering boots that take crampons, worn in before you fly. Beyond those you need crampons, an ice axe, harness, helmet and jumar, glacier goggles and UV sunglasses, a down or synthetic insulated jacket, a waterproof and windproof shell, a cold-rated sleeping bag, and a headlamp with spare batteries. Most of it can be rented or bought in Kathmandu, and the climbing hardware on this trip is provided. Carry your passport, permits, photocopies and passport photos in your daypack, not in the duffel the porter takes.