Pope Francis led Angelus prayers at Saint Peter's Square in the Vatican before thousands of pilgrims, two days after leaving hospital following a hernia operation.
The pope expressed his gratitude to those who had sent him messages of support during his stay at Rome's Gemelli hospital as he spent ten days convalescing.
"I want to express my gratitude for the affection, the concern, the friendship" expressed in those messages of support, the Argentine pontiff said, following his third stay in hospital in the past two years.
"This human support has been a great help and comfort to me," he said to cheers and applause from the thousands assembled in the square.
The 86-year-old has suffered a series of health issues since his election in 2013, from hip problems, knee pain and weight gain, to an inflamed colon and respiratory infection.
He underwent a three-hour operation under general anaesthetic on 7 June to remove a painful hernia on the site of a scar from a previous surgery.
Pope Francis reiterated his "profound sadness and pain" over last week's trawler sinking off Greece, which resulted in the drownings of at least 78 migrants aboard with hundreds more missing.
"It seems, it seems, the sea was calm. I renew my prayer for those who lost their lives and I urge everything be done, always, to prevent such tragedies," he said.
He also condemned Friday night's "brutal attack" by suspected jihadists on a school in Uganda where 41 mostly student victims were killed while others remain missing.
"I pray for the young student victims of the brutal attack against a school in western Uganda," the pope said during the weekly Angelus prayer.
While able to take weekly prayers and looking in good form following his latest hospital stay, the pontiff has cut back his commitments for the coming week, notably cancelling a weekly audience Wednesday.
