How important is the assurance of salvation in your life?

J. C. Ryle says,

Assurance [of salvation] goes far… It enables you to feel that the great business of life is a settled business, the great debt is a paid debt, the great disease is a healed disease, and the great works a finished work; and all other business, diseases, debts and works are then by comparison small. In this way assurance makes you patient in tribulation, calm under bereavements, unmoved in sorrow, not afraid of evil tidings, in every condition content, for it gives you a fixedness of heart…