You see, sometimes we are fooled into believing that everyone wants to go to Heaven, but that isn’t true. Heaven is not your own personally designed paradise; it is the Kingdom of God with all of its values: forgiveness, chastity, love of all (including our enemies), and generosity, among many others. In addition, God is at the center, not us. Many people don’t desire some or all the values of the Kingdom of God and thus die in a state of indifference or opposition to what God is offering. For example, some do not want to love their enemies or live chastely. A loving God will not force them to love what or whom He loves.
It is both foolish and presumptuous to think that when we die, we will suddenly start liking what we have disliked all our life or loving those whom we have not loved. What you love here on this planet is what you will desire in the world to come. When we die, it is my belief that our decisions and desires are forever fixed. One of the saddest thing about those in Hell is that their earthly life demonstrated that they would be even more miserable in Heaven.
That is why it is of the utmost importance to develop God's desires for our lives before they are permentaly fixed through our death. Let me be blunt, if we live a life devoid of the things of God, not caring about our relationship with Him which we develop through time in His Word, prayer, and most importantly, growing in our love for Him which will then parallel our desire to obey His commandments. Either we recognize that we are His, not our own, or we will spend eternity apart from the One who loves us the most. If you are lucky enough to have a devoted pet, such as a dog for instance, it quickly becomes apparent that the best of these creatures desire nothing more than to please us. Even a animal quickly recognizes that their obedience is a natural outpouring of their affection for their master. So why does this truth elude the heart and mind of man?
So we understand that life is a battle of desires. We must learn to want what God is offering and to eschew lesser or sinful things. St. Augustine wrote: "The entire life of a good Christian is in fact an exercise of holy desire. You do not yet see what you long for, but the very act of desiring prepares you, so that when He comes you may see and be utterly satisfied."
Let's close with some final wisdom from St. Augustine, “God is always trying to give good things to us, but our hands are too full to receive them.” Sometimes the presence of pain is a precious gift from God, for in His love He desires our sanctification, not just our happiness.