{ 1 } - seek our own happiness when this doesn't clash with other duties.
{ 2 } - always seek our own happiness regardless of other considerations.
{ 3 } - never seek our own happiness.

Kant says that we have a duty (at least an indirect one) to promote our own happiness. An unhappy person would likely get discouraged and neglect other duties.

There's a moral worth in pursuing our own happiness when we're motivated by duty (and not just by natural inclination).