Love is not a sentiment. Love should not be reduced to simply the way someone makes us feel. Of course, love comes with tremendous emotion and real feelings. But it is so much more. Love is a decision. It is something that we choose to give and receive, not something that we wait to experience.
We are programmed to seek pleasure, move away from pain, and do it all with the greatest economy of energy. The idea of running a marathon, on the surface, is preposterous. Unless there is food under that dumbbell, you are not programmed to pick it up. If there was a crocodile in the pool with you, it would make sense to swim as fast as you can.