Here's an interesting statistic for you (granted from the USA):
When I stumbled upon this article, I had to read the list twice, really? Being a QA Engineer is the second happiest job!? Someone had better tell that to some people I work with... I joke ;)
What is it that makes this job so happy then?
To me, it's the challenge of learning new things on a constant basis, the past few weeks have been spent trying to get my head around Espresso an automation API from Google for Android apps, I haven't spent as much time as I would have liked with it, but it's definitely challenging, and very rewarding. If I get to spend a whole day on it, then that does make me happy, so there's that I suppose.
Then there's the opportunities to constantly try and think of better ways of doing things, improving how we test so we can spend more time well, testing. It's rewarding coming up with tools or processes that improve peoples work life, just over a month ago I wrote a small program that would update a number of acceptance tests against a PBI in TFS, to save my team from doing it manually, things like that make me happy, knowing they can spend less time doing laborious tasks and more time doing what they enjoy.. Testing.
There's also the argument that regardless what happens, if you have a deployment to a test environment that isn't working, then you've found bugs, you've found issues, you can try and fix it... or if it is finally working, then great! You've got it working. Eric Jacobsen describes it a bit better here (and also the inspiration for this blog post)....
There's also the non technical side of things, being involved in communications from the start of projects, finding out what is going to happen, has this been thought of, really analysing what it is that is going to be developed. So working with a wide array of people, Business Analysts, Developers, Product Owners, Development Managers, you get to talk to so many people and you talk to them on different levels, which is really rewarding, and does make me happy.
So there you have it, these are just some of the things that make me happy, I'm definitely interested in what makes you happy as a tester? And also interested as to what makes Database Administrators so happy!? I think I might go and ask that question now!!!