Source

Pope Benedict XVI is almost 86 years old, had a stroke in 1991 that reportedly temporarily affected his vision. He fell in 1992 and 2009, and also had either arthritis or arthrosis, a similarly painful and debilitating joint condition. His doctor also advised him against taking any more transatlantic trips. [Source]

Here’s what came in his resignation letter:

Dear Brothers,
I have convoked you to this Consistory, not only for the three canonizations, but also to communicate to you a decision of great importance for the life of the Church. After having repeatedly examined my conscience before God, I have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry. I am well aware that this ministry, due to its essential spiritual nature, must be carried out not only with words and deeds, but no less with prayer and suffering.

However, in today’s world, subject to so many rapid changes and shaken by questions of deep relevance for the life of faith, in order to govern the bark of Saint Peter and proclaim the Gospel, both strength of mind and body are necessary, strength which in the last few months, has deteriorated in me to the extent that I have had to recognize my incapacity to adequately fulfill the ministry entrusted to me. For this reason, and well aware of the seriousness of this act, with full freedom I declare that I renounce the ministry of Bishop of Rome, Successor of Saint Peter, entrusted to me by the Cardinals on 19 April 2005, in such a way, that as from 28 February 2013, at 20:00 hours, the See of Rome, the See of Saint Peter, will be vacant and a Conclave to elect the new Supreme Pontiff will have to be convoked by those whose competence it is. [CNN]

As you can see, his arguments are not convincing at all and very doubtful.

On a serious note, the pope’s resignation might pave the way for electing the first black pope in the Catholic Church’s history. Read more about Cardinal Peter Turkson [Here].