It's true, that the last day of the week is Shabbat, having never changed, but after the Faithful Son has come, some wondered if it were like the manner of not eating certain meats. If it could be kept in faith, like all things. It often brings confusion, but I believe Paul taught us best in the matter so that we'd not stumble before our Father, and His Holy Anointed Son.
Always keep the commandments, and do so in faith, or else how will it be counted to your righteousness?
I believe in keeping all days Holy to the Father, since He is KING of them all, not just the last day, so don't fool yourself.
Be as the Son was, but keep in mind what His sacrifice has done for us all in cleansing us of our sins; it has given us liberty, not to be abused, but to be enjoyed, as we remain faithful and believing in His resurrection and works and teachings. Keep the fear in the Father, but don't let it turn into doubt for what the Son has brought, because He wants you to place your trust in His Way, so that you might be redeemed.
Keep away from worries, and your mind should be clear for all tests and tribulations which come your way.