It can be eye opening to add up the costs of hobbies. Recently, I did this using a decade of information. Given the ongoing "Great Recession", you may assume that I regret my hobbies. Not so. I believe that the benefit from each hobby can be far greater than their costs.

Education: Hobbies expose us to new disciplines and ways of thinking. While not equivalent to formal training, the education of a hobby is driven by our passion. We specialize in the areas that most excite us, and we don't get burned out on details that don't interest us. The new concepts may spark ideas at unexpected times as our minds builds new relationships.

Therapy: Hobbies are often distant from what we do for a living. Hobbies can an excuse for our minds to explore new territory. Learning new skills and using new tools can simply be therapeutic. I find working with my hands clears my mind and is peaceful.

Friendship: Many of my best friends I've met because of hobbies. These friendships are priceless.

Employment: A hobby may later turn into a business or a new vocation. While the hobbyist may not be formally trained, they may be more passionate and often that's more important for productivity.

Pass it on: Ebay is full of others moving from one hobby to another, but also consider donations. Where possible, try to stay in touch with the person who takes up your hobby. While you may not be active in that hobby any more, you can provide sage advice and continue to experience the hobby vicariously.