Ananda was the Buddha's personal attendent for the last 20 plus years of
the Buddha's life. Besides attending to the Buddha's personal needs, his other
duties included representing Buddha on occasions, memorizing the Buddha's speeches,
repeating the Buddha's speeches in his absence, and being messager for the Buddha.
So, he really had a very busy job!
He was so busy that he didn't even have time for his own practice. [Ed - Even without any spiritual cultivation, Ananda was said to be the kindest and most loving of all Buddha's disciples. I suspect he didn't have any time for himself partly coz he spent his free time helping other people]. So by the time the Buddha died, Ananda had still not attained Enlightenment. When the Buddha was dying, Ananda cried. In contrast, enlightened monks accepted it with calmness.
Anyway, only after the Buddha died did Ananda find time for his own practice. At that time, the Arahat Maha Kassapa, another one of Buddha's main disciples, was organizing the First Buddhist Council, a gathering of all Buddhist monks to organize and consolidate all of Buddha's teachings. Ananda was determined that he wanted to be Enlightened by the time of the Council. So everyday, he meditated very hard.
As the day of the Council was drawing closer and closer, Ananda still seem nowhere near Enlightenment.
The night before the Council, Ananda tried very very hard. But still, he was getting nowhere. It was getting late. Finally, he decided, "Maybe I'll relax and work for Enlightenment after the Council. There is no need to hurry now". Thinking so, he laid down to rest.
It was said that the moment his head touched the pillow, he attained Enlightenment.