Musar for Makkot 46:3

G–d saw fit to reveal the remainder of the 613 commandments to man in His own good time, i.e. to the generation of Israelites who were released from bondage in Egypt. Since that time every Jew is expected to perform as many of these 613 commandments as his particular station in life enables him to perform. The key to his achieving perfection by such מצוה performance lies in the manner in which these מצות are fulfilled. If they are all fulfilled joyfully, then the "preparedness" of which we spoke earlier is enough to credit such individuals with also having fulfilled those commandments which they were unable to fulfil through no fault of their own.