God is all holy. Even if I become a great saint, compared to the Lord, I would still be unholy. I believe that how much we desire to be holy matters a lot. Where we fall short, God's mercy will cover. If you think that being holy is not cool, you've been brainwashed by the world. If you love the Lord and want to follow him, you are called to be holy. If you think that's an unattainable goal, then it's you who are limiting both yourself and God, not God. In Matthew, Jesus said to his disciples, "Be perfect, just as your heavenly Father is perfect" ~ would the all-knowing Lord ask for the impossible from us?
In any case, holiness is being Christlike. Holiness is knowing that you are in God's good company. Holiness is refreshing, uplifting, and a joy. It is feeling victorious and secure in the Lord. It is experiencing freedom because the world no longer has a hold on you. When you're holy, God smiles. Being holy is the highest state of human existence. It definitely is cool.
For Catholics to become as holy as possible, seek complete union with the Lord through receiving the Most Holy Sacrament, the Holy Eucharist.