What does it take to be a Catholic nowadays?

We don't need to be saints or martyrs to achieve the eternal peace alongside God. We need to be holy. And holiness is in the small things. I'm currently reading 'The Karamazov Brothers', by Fiodor Dostoyevski, and there was a stretch I found really interesting, told by the Elder Monk Zosima: "For joy is the purpose of all men, and whoever were perfectly and completely joyful has the right to say 'I have accomplished God's will on Earth'. The just, the saints, the martyrs, all of them were joyful." Note that he says 'joy', and not 'happiness', for happiness is transitory, and joy is lingering. If you live for happiness, you are a prisoner of circumstances because if the circumstances change, then you are not happy anymore, as says Philippians 4:4. Some sins may make us happy, but we can only find true joy in Christ.
So there comes sin. All sins diverge us from God, but we all know how good and merciful He is. His agape love is incomprehensible for us mainly because of it's infinite forgiving nature. This is one of the main messages all over the Bible. He is the Good Shepherd, that will leave all the others only to save that one lost sheep. He is the Father that welcomes back the prodigal son. He loves us too much, and, of course, wants everyone of us to be with Him eternally, in Paradise. That's why He makes it all so simple: regret your sins, and you will truly be forgiven, no matter who you are, and no matter what you've done. That's conversion. And we need to convert ourselves frequently.
But even though, heaven isn't granted for anybody. That's a common silly mistake that often mislead us from God. Not because I'm Catholic my place in Heaven is for sure. No, it's not something mechanical. It's common for us to think like it's a balance, so if your good things outnumber your bad things, you're a saint and your parking lot in paradise is just waiting for you. We must go to the Church not to grant our salvation, but seeking the ways to have it, as it will always give us all the support we need. But then, how do we proceed after that is on us. So, where to start?