Skill lets you respond to situations that motivation never predicted.

Motivation prepares you for the situations you imagined. Skill lets you handle the ones you did not, since it is general and applies to conditions nobody predicted. Enthusiasm is specific to a plan and evaporates when the plan does not match reality.

Invest in capability rather than in psyching yourself up. The situations that actually arrive will not be the ones you were motivated for, and only the skill will still apply.