One key thing I've learned is to hit a sweet spot on exertion -- respiration is increased, while heart is working but not beating too hard. If the heart starts going too fast, I slow down, period.
thx123, I've found this to be true for myself as well. Don't let competitiveness or excitement rush you. I've noticed on several trips that the moment I exceed my usual comfortable pace, the headaches start, and they will not go away until at least an hour after leaving the mountain. This is a problem I usually have when going by myself. I think I'm still at sea level and try to go at that pace. When I'm with another person, we naturally slow down because we have a conversation almost the entire way.
