Charles Ellicott Commentary Ecclesiastes 5:20

"For he shall not much remember the days of his life; because God answereth [him] in the joy of his heart." — Ecclesiastes 5:20 (ASV)

“In the enjoyment of God’s gifts he does not think much of the sorrows or brevity of life.” This is the usual explanation; and though not satisfied with it, we cannot suggest a better.