I think the best thing to focus on is how much value and happiness you can bring to others. Not something self-centered such as expertise that perhaps nobody else would even notice because it's meta. Expertise should not the end goal, but instead a facilitator to value creation.
For example, if you're making a song, your thinking should be "I can't wait until people hear this song!", not "I can't wait to slightly increase my skill".
For example, if you're making a song, your thinking should be "I can't wait until people hear this song!", not "I can't wait to slightly increase my skill".