Each person should be fully convinced about observing special days, thinking and deciding for himself and not for others. We should try to please God by everything we do.

Romans 14:5-9

5 Some people regard certain days as holy and think that the other days are not holy. Other people regard all days as equally suitable for worshipping God. Each person should be fully convinced about such matters, thinking and deciding for himself and not for others. 6 As for those who believe that they should worship on a certain day of the week, it is to honor the Lord that they worship on that day. And as for those who think that it is all right to eat all kinds of food, it is to honor the Lord that they eat those foods, as is clear from their thanking God for the food that they eat. As for those who abstain from eating certain kinds of food, it is to honor the Lord that they do not eat those foods, and they also thank God for the food that they do eat. So doing either of those things is not wrong in itself. 7 None of us should live merely to please ourselves, and none of us should choose when or how we will die, merely to please ourselves. 8 While we live, it is the Lord whom we belong to and should be trying to please, and not just ourselves. And when we die, it is the Lord whom we should be trying to please. So, while we live and also when we die, we should be trying to please the Lord to whom we belong, not just ourselves, 9 because the very purpose for which Christ died and became alive again is that he might be Lord whom all people should try to please, both of those who have already died and of those who are still living.