Choose the correct tense

In 1990, two friends Robert and Barry managed to survive the harsh conditions of the Sahara desert alone for two days. The two friends [had enrolled|had been enrolling] in the Marathon of the Sands which was a seven-day foot race through the Sahara desert. Before the competition began they [had packed|had been packing] all the food, clothing and supplies they needed on their desert adventure in large rucksacks, which they carried on their backs. On the first day of the event the two friends [had walked|had been walking] in the desert for a few hours when all of a sudden a sandstorm appeared out of nowhere. They had nowhere to take cover. Robert opened his rucksack only to realise that he [had forgotten|had been forgetting] to pack their compass. Terrified, the men sat in the middle of the sandstorm and waited for help to arrive. They [had waited|had been waiting] for two days before the organisers of the event realised that the two men were missing. The organisers sent a rescue team which eventually found them. The two men felt extremely lucky to be alive!