"One person considers one day more sacred than another; another considers every day alike. Each of them should be fully convinced in their own mind" (Romans 14:5, NIV).
What matters to you matters to you. And it SHOULD matter to you. Understand WHY it matters to you. As you grow in your relationship with God, there will be things that He will show you that will be paramount in your spiritual growth. Learn what God is showing you, but know the difference between His direction for you and His truth. Direction is specific and may not apply to everyone. Truth is absolute and does not change.
In Romans 14, Paul addresses those who have begun arguing about invidual convictions they were passing off as absolute truths. What was important to them caused them to become offended when others didn't share their level of importance. When people don't see important what you hold as valuable and sacred, it is easy to feel invalidated. It is possible for people to understand for you, but not agree for themselves. There are those who feel it is a sin to go out to eat on a Sunday, while others see it as a time to share and build relationships in the name of Jesus. One might judge the other, but should be cautioned to keep their eyes on Jesus and what He has spoken to them.
Some things aren't a matter of morality and absolute truth, but of personal direction and conviction. Hold fast to what is important to you withoutt passing judgement on others for holding on to theirs. Continue to seek truth from the Word of God. When it's black it's black and where it's white it's white. Don't get stuck in the gray areas, and don't attempt to darken or lighten the gray areas in your own interpretation. After all, when judgement or cycnism creeps in and begins to take over your attitude, you have slipped from gray into the black and white. Focus on where Scripture is clear and trust God to guide you where it seems a bit gray.