Yes, design can make you happy.
To be a good designer, you would need to have deep and far-reaching interests outside of the profession.
Drugs feel great in the beginning and become a drag later on.
Being in a foreign place, preferably for the first time, having seen many things and collected new impressions, and returning to an empty hotel room with an hour or so to blow. That mix often yields fine results.
Work your ass off. Don't be an asshole.
Any excuse to get away from the computer screen is welcome.