Sometimes it is really hard to sit in the single and go for a row. I think this is really normal. I, like probably a lot of people, burn out every once in a while. What I have learned from my own experience is that there are two reasons for it to happen. It is that I am either physically tired or mentally tired. If either of these are the case, the wisest decision is to blow off practice. Blowing off practice is healthy. I didn't understand that until I was so burnt out that I wanted to make scrap material out of my single and my oars.