I am curious how exactly does one love Jesus in the heart. I already have my mind set that I love him in my head, but how do I feel that connection in the heart (like for example when I love a girlfriend/wife)
That is a good question. Just to illustrate how good a question, let me ask, how do you love a wife or girlfriend in the heart and not just in the head?
It's not something that can really be explained; in fact, if you could explain it all, it would lose a little something in the process. But when does one cross that line between initial attraction and love? You could say it's when you think of her all the time, but even then if that is love it is only the birthing pangs of love. By the time you reach the point you would do anything for her you've found yourself firmly within the halls of love. And what steps brought you to this point?
I would think as with any type of love, be it that of a romance, or even that of friendship, the key is time. It would be a poor sort of love that did not want to spend time with the beloved, it would be a poor sort of friendship where one does not know one's friends. It is the time spent, the pleasures of company, and the terrors of shared trial and tribulation that water and feed the infant blossoming of love into a healthy plant in full bloom.
So it is with love for Christ. To turn an intellectual love into a love of the heart you must spend time with Him. Start with the Gospels to get to know the actions of the God-Man, the Gospels shed light on the teachings of the Epistles, and the two together will shed light on the Old Testament, so that from Genesis to the Apocalypse you get to know the person and actions of Christ throughout human history.
Also, there is prayer of the corporate and private varieties, but always keep in mind that in reality all prayer is corporate. When we pray at Church we pray in the visible presence of the Body of Christ, present all round you, in the people you are with and in the Flesh and Blood on the altar. When we pray at home this presence is not as visible, though if you pray with family it will be evident. But regardless of the prayer being with family or alone "in your closet" you are still praying with all the saints, past, present, and future, you are still a part of that Body of which Christ is the head. I would add in this section to read the writings of the Fathers of the Church, both to ensure a correct reading of the Bible and to get to know the way that the Body of Christ has received these teachings.
Through the knowing of the Bible and prayer (the two being our conversation with God), we should start to feel our love for Christ growing naturally. Love for Christ has many times been likened to romantic love, but here we find something strange, like and unlike at the same time. For while it is the province of romantic love to become so enraptured with the beloved that all else seems a distraction, true Christian love evidences itself in the love we show others. It would be seen as odd if, professing love for Sarah, I spent most of my time with Jenny and Anna. But odder still is the Christian who has no time for others, who ignores the man who needs help or the people in need. Even our monastics, who most like romantic lovers seek seclusion to spend time with our Beloved, don't react harshly (like a man on his honeymoon when housekeeping shows at the door) when interrupted from their contemplation by those seeking healing and guidance, but with joy at being able to share the love that our Beloved bestows upon all (of course, too many interruptions and they may seek more remote and secluded areas. But even then, those in need always seem to be able to find them, and in even greater numbers).