Making it part of your job somehow is clearly the best option, especially if you want to play mostly at private courses.
Then there are the obvious options:
Play at public courses. Walk rather than rent a cart. Move somewhere that has cheaper greens fees. Look for deals on greens fees (around here there are tons of half price coupons to be had, especially for week day play, probably because the market is flooded with so many courses.)
If you want to play all the time at the same really nice place, then a private course might be an okay deal. But beware of fees that can ratchet up at any time. The one where I used to live had a monthly fee that wasn't too bad for people who played 5+ times a week. But then they moved to requiring cart rental every time, and that jacked things up for the frequent playing walkers. Private courses also tend to have policies that are antimustachian (like you can only have beverages you purchase from their roving beverage girls, or you have to spend $200 a month in their restaurant, etc.)