1: Don’t underestimate the altitude
No matter how fit you are at sea level, the high altitude levels that come with trekking to Everest Base Camp put your body through a completely new challenge. Parts of this trek are quite deceiving to the eye, and the appearance of more gradual ascents on the route can give people a false sense of security.
Try not to become complacent. You may be able to walk 1km or a mile uphill at sea level with ease, but that same journey at high altitude leaves you feeling like you're wading through sludge. Getting overconfident and moving too fast can result in serious altitude sickness, forcing you to abandon your trip. Take your time and pace yourself, and you should complete the trek with relative ease. Our Chief Experience Officer prepped us by demonstrating a safe walking pace so that none of us overexerted ourselves.
Even with acclimation many trekkers feel altitude sickness, which can bring on nausea and headaches. Medication is available to lessen these symptoms, which made things easier.