God calls us to love Him with all of our heart, soul, mind, and strength. This means that other things which demand our ultimate allegiance must be rejected. Another way to say this is that the cost of following Jesus is total. For many this sounds extreme and enslaving because we assume that we have a right to serve ourselves (and not God) and thereby find freedom and fulfillment. But God made us to serve Him so completely that we lose our life, and when we do, by way of  one of His deep paradoxes, we truly find it.