The Cuban leader said only that he would continue writing articles called "Reflections of the Comandante" in the Cuban press.
He has written a series of 14 articles from his convalescence quarters, most of them scathing attacks on George Bush, the US president.
Asked if he was in good spirits, Castro said: "Yes, yes, I am doing what I have to do. There are no secrets anymore. I have said I am eating better for the first time."
The recorded television interview came after Castro met Nong Duc Manh, Vietnam's Communist party chief, over the weekend.
|Castro, right, met Nong |
over the weekend [Reuters]
Despite greying hair and slower speech, he appeared to be in an upbeat mood when he recalled a visit to North Vietnam in 1973 in the midst of its war with the US.
Castro underwent several life-threatening surgeries due to an undisclosed illness thought to be diverticulitis, or inflamed sacs in the large intestine, that sidelined him from power 10 months ago.
His last public speech was on July 26 last year just before he was rushed to hospital.
Castro handed over power temporarily to his brother Raul five days later, the first time he has stepped aside since seizing power in a 1959 coup.
Spanish-language channels in the US interrupted regular programming to air parts of Tuesday's interview.
There were no tough questions on his health or domestic issues but his appearance heartened some supporters.
"He has put on weight and looks much better," said Lazaro Rodriguez, watching Castro in his Havana home. "We're happy to see him recovered and about to resume duties. We need him."