The Prophet used to say supplication in these words: "Allahumma inni a'udhu bika minal-kasali, walharami, wal-jubni, wal-'ajzi, wa min fitnatil-mahya wal-mamat. (O Allah, I seek refuge in You from laziness, old age, cowardice, and incapacity, and from the trials of life and death.)"
Sunan an-Nasa'i Book 50, Hadith 62