Why those the boy say he is thoughtless?

The boy believes himself thoughtless because he hasn't thought ahead and anticipated Santiago's needs.

Where did you wash? the boy thought. The village water supply was two streets down the road. I must have water here for him, the boy thought, and soap and a good towel. Why am I so thoughtless? I must get him another shirt and a jacket for the winter and some sort of shoes and another blanket.