United Kingdom, March 4 -- Barry Manilow's cancer battle has been "agony" because he has been unable to perform.

The 82-year-old singer announced in December that he was delaying his farewell tour after a cancerous spot was found in his left lung, and late last month, he rescheduled some upcoming concerts because of his health.

And while Barry has reassured fans he is getting "stronger", he admitted he's found his illness difficult because he has "no patience" and has been desperate to return to normal life.

Marking his song Once Before I Go becoming a top 10 hit on the Adult Contemporary chart, extending his run to six decades, Barry said in a video message to fans shared on social media: "It's been a long ride and since I have no pat...