A friend of mine was asking about the vow I took, and shared some struggles with some spiritual disciplines in the past. I emailed him this response, which though short, and not very deep, explains things in my way of thinking:
But I wanted to talk to you about your fasting, and the spiritual disciplines in general. When we do these things, it is important for us not to look like we are somehow bargaining with God. Like, I did this so you have to then do this. This makes God into another product that we buy, not with money but with acts of devotion. It is so easy to fall into this ideology. Remember Jesus talks about the disciples fasting when he is taken from them. The best idea to remember is we do these things not to earn anything, but rather that the exercise would allow us to set our hearts aside towards a realization of Jesus, and his love, and his presence.
It is for us to abandon ourselves to God's love, this is our call. I like to think of a wife and husband relationship. Imagine if I told me wife I was not going to eat for three weeks as a way of drawing closer to her, but then used meal times to watch baseball on television, was angry and short tempered, and often reminded her of my sacrifice and accusing her of not appreciating it, or returning the favor. Not very good work there is it?
So how can we use these as ways to grow closer? If I used the time I spent at meals to really talk and pay attention to her, if I spent the time we would spend shopping on reading our old love letters to each other, if I spent the money we saved from me not eating on a new dress for her (remember we give gifts to God by giving to the poor), and if every hunger pain was a reminder that I love my wife, and like food I cannot live without her. A bit different isn't it?
I hope that helps a bit.