Answer:
Honestly, this is a personal question. I can't help you fully but I can give some advice:
You should think to yourself about one time that you have experienced what Van Gogh had felt.
For example, during a sad time in your life if you had thought to yourself about the happy times/moments you had experienced with that item, person, or animal.
Hope that helps, the example is not fully accurate though.
Because Thomas Carlyle who was a writer and philospher, made up the phrase that economics is "dismal science" (dismal meaning depressing) because he believed that humans are trapped in a world where population will always grow and limit natural resources and bring widespread misery.
King Charles I was forced to sign the petition of rights