Don't tell him how he should feel. Then, let him take part in the plan for how to avoid future problems. In the above example, maybe the child needs a set of play clothes waiting in easy reach, or a smock in the area where the paints are. Most important, when you speak to a child about the mistakes he's made and how you would like him to do things, help him learn what was wrong about his behavior and what he could do in a similar situation that is good behavior. But never put down the child.
Chores are often a bone of contention between older children and parents.
Many of us have only ourselves to blame. Most young children think everything adults do is fascinating and they want to imitate us, but it is so much easier for us to do the work ourselves that we rarely allow the young children to really participate in our chores. By the time they are old enough to be really helpful, they haven't developed the skills or the habit of participating. Even at an older age children need parental input on chores. Sometimes a task like cleaning a room just seems so enormous that an occasional helpful suggestion as to what to do or how to do it can be tremendously motivating.