Here's a classic relationship marketing tip that still works - and for many is their main method of doing business. Seek and play with your significant business contacts.
"Working" on the golf course or tennis courts as a means of solidifying and building relationships isn't a new idea and of course not for everyone, but just because this behavior has been around for a long time doesn't mean it no longer works. Golf and tennis continue to draw 100's of thousands of business people on regular schedules who have fun, get exercise, and do business.
Golf and tennis aren't the only outlets, of course. Adult soccer, rugby, and lacrosse leagues, certainly bowling leagues, running, biking, and swimming clubs, the list goes on and on of active sports activities where adults congregate and do business.
Often there are other events and opportunities before, after, or associated with group athletic pursuits that may involve other activies together or even include other family members.
It is also easy to lose sight of the marketing purpose that might have initially justified the play, however, so watch out for signs that you're actually avoiding work in the name of "marketing". For example, if you play golf with the same three other guys every week, that activity is hardly expanding your customer base. Also, while drinking and gambling are often a side element associated with some sporting pursuits (golf is especially associated with betting), if involvement in any sport is really an excuse to get plastered or if gambling gets out of hand, the effect on your business as well as your life can be the opposite of the original intention (at least the original "stated" intention).
Shared physical pursuits, whether in service projects, charity walks, or active sports participation are a powerful way to contribute to the community and enjoy life while simultaneously building business relationships.