The meaning of the ancient poem "Light Rain on the Sword Gate Road"

Full poem translation: The clothes are stained with dust from the journey and traces of messy wine. When you go out and travel to far away places, there is no place you visit that does not make you feel gloomy and sentimental.

Should I be a poet in this life? Why mount a skinny donkey and ride to Jianmen Pass in the drizzle?