The Cuban leader, Fidel Castro, has admitted he does not have the physical strength to speak publicly as part of campaigning for upcoming elections.
Brazil's Lula, left, says Castro is in "impeccable" health
In an essay for state media, the man once famed for marathon public speeches said: "I do what I can: I write."
Video footage released later showed Mr Castro looking thin but lucid receiving Brazil's president on Tuesday.
The 81-year-old Cuban leader has not been seen in public for more than 17 months since stomach surgery.
In July 2006, he "temporarily" handed power over to his brother, Raul, but must be re-elected to the national parliament in Sunday's national poll if he is to remain president of the Council of State.
The 614 deputies chosen in the January elections will select the 31 members of the Council of State, whose president is head of state.
The President of Brazil, Luiz Inacio Lula da Silva, startled some observers when he told reporters on his way home from Cuba that Mr Castro was in "impeccable health" and ready to resume his political role in Cuba.
In the video footage aired on state media on Wednesday, Mr Castro appears wearing his now-trademark tracksuit.
In the footage - the first seen since mid-October - he looks gaunt but alert, telling President Lula: "I have felt quite well."
But in an essay printed in the state newspaper Granma on Wednesday, Mr Castro says his health prevents him from going out to campaign in the neighbourhood which has put him forward as its representative in upcoming elections.
"I am not physically in a condition to speak directly to the citizens of the municipality where I was nominated for our elections next Sunday," Mr Castro says.
"I do what I can: I write. For me, this is a new experience: writing is not the same as speaking. Today, when I have more time to inform myself and to meditate about what I see, I have barely enough time to write."
Mr Castro spends only a few sentences discussing his state of health, using most of the rest of the article to criticise the US President George W Bush.
He condemns capitalism as a "tree with rotten roots, from whence only the worst forms of individualism, corruption and inequality sprout".