You have to work on something you are passionate about. If you work on Sundays because you cant keep yourself away from it, then great. If you work Sundays because you think if you work hard enough you will become rich and successful, then you are likely going to burn yourself out. Your life is NOW, be happy now. Don't push it off. If coding all day makes you happy do so. but if you rather hang out at the beach do so…
and it will spill.
Keep sharpening your knife
and it will blunt.
Chase after money and security
and your heart will never unclench.
Care about people's approval
and you will be their prisoner.
Do your work, then step back.
The only path to serenity.
-- Tao Te Ching, ch. 9, Stephen Mitchell translation (http://taoteching.org.uk/index.php?c=9&a=Stephen+Mitchell)