Your hero needs to be sympathetic (so your audience will care) and your hero needs a clear goal (so your audience knows what your hero is trying to do). Without a clear goal, your audience will simply lose interest.
In the beginning, make your hero’s goal clear and force the hero to pursue it. In “The Little Mermaid,” Ariel dreams of being with the humans. This point gets driven home multiple times by her hanging out with a seagull, collecting human artifacts, and even spying on a human ship to watch people dance and sing.
Ariel’s apparently been doing this for some time and then she falls in love with a young man she sees on the ship. Yet even falling in love isn’t enough to push her into the human world. It’s only when her father destroys a statue of the man she loves that Ariel finally agrees to make a deal with the Sea Witch to become a human.
The basic formula is to give your hero a goal, show the hero wanting that goal, and then finding a way to force the hero to react.
In “WALL-E,” WALL-E wants to find love, which he dreams about by mimicking an old video he’s salvaged. Then he gets his chance when Eve arrives and he follows her around, eventually winning her trust until a rocket ship takes her and WALL-E is forced to chase after her.
In “Star Wars,” Luke wants to escape the dead end world of his desert planet. He dreams of adventure, but until Darth Vader’s storm troopers slaughter his aunt and uncle, he’s never motivated enough to take action.
Your hero has a goal. You reinforce this goal in multiple ways. Then you force your hero to pursue that goal.
Bruce Willis wants to get back with his wife in “Die Hard.” He tries to keep from losing his temper around her and when things start looking promising, he gets angry and starts losing her again. Then the terrorists strike and he has no choice but to save her life if he ever wants to get her back again.
Without a clear goal, evidence that the hero really wants this goal, and an outside force that shoves the hero towards achieving that goal, your hero’s story will be incomplete. In sports, it’s easy to cheer for a team when you know what the goal of the game is. In the same way, it’s easy to cheer for your hero when you’ve defined the goal of your hero.