A big part of parenting is teaching kids self-control. Yes, sugary snacks do taste good, but even so we shouldn't eat them too often. Yes, we know that math homework may not always be fun, but it must come before TV. Yes, soccer practice may seem tedious, but it's the road to excellence on the field and beyond. And so forth. No parent disputes this. It's in the manual.
Indeed, we're all expected to take this life lesson on faith. Hard work and effort are virtues worth instilling, and worth having.