In reality, it's pretty hard to consciously make yourself want something (at least for most people), as our conscious brain does not have that much of an effect on our emotions. In practice, what I've found out I (my conscious brain) can do is alter my circumstances - don't store nice food at house so that it's harder to snack, work from the office (not from home) so that it's harder to procrastinate or get so fat that I no longer feel good in my body.