Exhausted, my heart pounding, a throbbing headache that painkillers would not shift, and unable to sleep. I was feeling very low. I was, however, high up a Himalayan mountain in Tibet at 4,300m (14,100ft), and where I was now struggling with the effects of the altitude.

Getting up here had been no easy task, riding up the steep mountain path on horseback. The horses were small but strong, with wooden saddles and colourful Tibetan blankets. We were guided by a group of tough Tibetan horseman. My camera equipment packed in bags and secured to the packhorses along with the camping gear. I carried my camera over my shoulder.

I have been filming with Richard Quest on an expedition with China's foremost explorer Wong How Man. High above us was our goal the remote Nienguo Monastery, where we were probably the first Westerners ever to visit.

Filming from horseback would be challenging in a normal situation, let alone at altitude. I frequently had to dismount and run ahead to film Richard and Wong How Man coming towards me on their horses. To keep a steady picture I try to control my breathing or even hold my breath for the duration of a shot. With less oxygen, this was becoming impossible. Instead of recording the sound of horses hooves on the rocks, I worried my deep gasps for air were instead being picked up by the camera microphone.

The views from the mountain were getting more spectacular and the route the horses took more treacherous. I tried to forget the steep drop inches from the horses hooves. Suddenly one of the packhorses bolted back towards us, knocking over the producer Matt Percival and causing his horse to bolt off as well. He was bruised but able to walk. Our guides went after the horses. A little shaken, we continued our exhausting ascent on foot.

Out of breath we arrived at the monastery, and the heavens opened, hail stones bounced around us. I felt it was a sign we were not worthy to visit such a redeemed and holy place. We ran for cover in a Tibetan Stupa, with old prayer wheels, and adorned by prayer flags. Once I had caught my breath and took in the serenity and beauty of the monastery, the hail gave way to glorious sun. The friendly monks, unaware we were coming, welcomed us and let us pitch our tents.

The whole experience was breathtaking - literally. In fact there is 30 percent less oxygen at this altitude. By the end of the day I was exhausted, just picking the camera up sent my pulse racing and head throbbing. I felt I had pushed myself further than I probably had done before.

The next morning I was looking forward to returning to a more comfortable altitude. But this was not without incident. Strangely, at the same point as the day before, the same packhorse bolted. Our Tibetan guide thought it must have seen a ghost on the path. The horse disappeared off the edge of the mountain path, tripod and camping equipment still attached. I decided riding Tibetan horses was not my style, and walked back down to the valley.

I had poetic visions of the expensive CNN tripod one day ending up on a Tibetan mountain with prayer flags attached. But later one of the horsemen discovered it and brought it down. The last we heard the horse and camping equipment had not been found.

Watch Richard Quest's report

From Neil Bennett, CNN International Cameraman