Yes, altitude becomes the major factor for most people, because they are not acclimatized with such altitude. The lack of oxygen creates altitude sickness. It was my first time to reach such heights, so I got a mild headache, and body went lethargic, so yeah it was very tough, especially the last 2 kilometres while reaching the top at 5200 metres altitude. That you saw in video, I spoke Hindi in there, but you understood my tone, bravo! Actually I talked the same thing in video, that is my exhaustion at that height.