I like to consider myself reasonably intelligent, and pretty happy, at least at this stage of my life. And I attribute a lot of my happiness to my intelligence.
A few of the things that my brain allows me to do:
Adapt
I know that I can survive in just about any situation; I’ve spent a lot of time proving this. I can figure out how to get nourishment, shelter, clothing, and start a base for long-term sustenance given almost any set of starting circumstances. This tends to make one feel pretty darned free.
Get Great Toys
The best things in life are pretty complicated. Computers, for instance, are sometimes a wee bit tricky. But to me, they make sense; I can make them do cool tricks. I can repair them. I can make weird stuff run on them. As it turns out, I can make a good living from them. And they are fun; man, are they fun. If you’ve never done a LAN party, you’re missing some amazing playtime.
Know My Priorities
I could be doing a lot more with my life. But I’m not. Know why? Because it wouldn’t make me happy. I have a job that provides me with money and interesting problems, and the US RDA of stress. Then I have hobbies… way too many of them. Late-night radio show. Guitar. D&D game I run every week. Painting. Sculpture. Old movies. New movies. There is so much to do, so much fun stuff to see and feel, that I will never have enough time to do all of it. Why spend all my time working?
Be of Use
I like to think that I’m a pretty useful guy to have around. Picking up skills is relatively easy for me; therefore, I tend to get called to fix swamp coolers, build dog-houses, read screenplays, edit resumes, and whatever else my friends need help with. I like being the kind of friend that people can count on, and being able to answer questions and be generally useful makes me proud.
Plan Ahead
I can often anticipate problems that will need to be dealt with in the future, and make arrangements to minimize them. I’m the guy who has a flashlight and extra water on what was supposed to be a two-hour daytime hike. I’m the one with the extra power cables at the LAN party. I’m the guy who takes the defensive driving course and the firearms safety course. It keeps me from having to deal with a lot of unhappy situations. I also preview my posts.
Make People Laugh
When I’m in form, I have a quick, strange wit. It makes the people around me laugh, and making people laugh makes me happy. There’s nothing as gratifying as reducing a roomful of serious business-types to helpless, tearful, nose-running laughter.
Research
I can also look up cites.
From Advances in the Understanding of Happiness, by Ruut Veenhoven. Published in French in Revue Quebecoise de Psychologie, vol 18, 1997, pp 267-293
So, I’d have to say it’s unrelated. If I wasn’t smart, I think I could find other things to be happy about. Intelligence is just a tool; what you build with it is up to you.