It is only valid for a lifetime and not for anything other than a lifetime. Fasting for a lifetime for a person is only to fast the Sunnah in its entirety, and that is not valid for him for the sake of the day of Fitr and Al-Adha, as breaking the fast on them is obligatory according to consensus, so for this reason it is valid, for eternity is the name of God and fasting is for Him, so what It was for God, so it is not yours. Rather, it is yours unless He prohibits it from you. If He prohibited it and it is not yours, then He has told you that it will not happen. If you do it, you act in a way that is not intended and you aspire to something that you do not covet .