The Lord shares His observation of people placing their offerings into the treasury with His disciples. He points out to them that while some people gave larger quantities of money, they only gave out of their surplus wealth. There was a poor widow who only placed two small coins into the treasury. He points out to them that because she gave from from her own livelihood that her offering was more than all the rest.
This continues the theme from Christ the King (click here to listen) and how we are to love God through the love that we have for others. Just like the offering of the poor widow, the gift of ourselves should not be limited to what is convenient. We hear in the Gospel that when we love God it is to be with all that we have and all that we are. Like the poor widow, we do not just give what we can spare, wee are to give without thinking of sparing things for ourselves. We are to give from our livelihood. The cost of selfless love is when there is a real giving of ourselves without considering the cost to ourselves.