He has carefully worked his way back — singing recitals, appearing as Fagin this spring and summer in the musical “Oliver!” at Grange Park Opera in England, and now returning to the Met as Don Giovanni, which he once recorded under the baton of Claudio Abbado but has never done in New York.

Mr. Keenlyside said that he did not believe his recent difficulties arose from his decision to begin singing heavier Verdi roles, which was seen as a daring choice for a lyric singer whom Gramophone magazine once described as “the best baritone singer and interpreter of Schubert this country has ever had.” He noted that Verdi had made it clear that he wanted versatile singers who could sing very softly when needed.

His vision of some roles has evolved over time. After breaking six ribs while singing Berg’s “Wozzeck” in Munich after slipping on a stage that had been covered in water, Mr. Keenlyside came to realize that he had been making the title character, an oppressed soldier, too “wacko,” he said, perhaps because he had been inspired by the way the actor Klaus Kinski approached the role in a 1979 film.

Indeed, Mr. Keenlyside said that he had come to realize that too much physicality in general could be merely distracting. He recalled that after one particularly acrobatic Britten performance, he had overheard a member of the chorus saying that he should be reminded that he was playing Billy Budd and not Billy Smart, a famous circus performer.

“It popped my balloon at the time,” he recalled. “But I thought, well said.”

Now Mr. Keenslyside, who has begun singing recitals with a small band and who loves to listen to the Mississippi Delta blues of Robert Johnson when offstage, is returning to the Met with Mozart, which he has long been renowned for. (He has already sung a standard-setting Papageno in “The Magic Flute” and Count Almaviva in “Le Nozze di Figaro” with the company.)

He sees all of the Mozart operas as ruminations on freedom — he even hears echoes of the tune later used in the “Marseillaise” in some of Papageno’s music — and said that he looked forward to singing “Don Giovanni” in New York, noting the disturbing way its composer makes his antihero title character much more seductive than the more earnest Don Ottavio.

It is a return that Mr. Keenlyside said he worked “very, very hard” to achieve.

“You have to ask yourself, same as you’d ask a young singer, how much do you want this?” he said, adding: “And if the answer to that is you want to sing, tighten your belt. Go!”