I have heard and read about this question quite a few times, without getting a very clear answer, though.
Probably, this is because the question as such does not really address the core of the issue it wants to raise.
In my view, both success and happiness originate from the same, and grow in a very similar way.
In order to be successful and happy, you must start with shaping your life around your core values, and not around those that your environment imposes on you. Only by doing so, you will be able to choose and develop activities that, both professionally and personally, can bring the fulfillment and the enthusiasm that are required in any successful endeavor.

Success can be a rather difficult concept to formalize, as its definition depends greatly on what you consider important for you in life. For some, this will be making lots of money, for others it will mean have a family, it also could be gaining a position of power or reach a certain social status; it could be becoming famous, and so on.
If you try to eliminate the subjectivity that goes together with the variety of values, a good definition of success that I have heard is that “success is to bring what you start to its completion”. I personally like this definition, because it describes very well the whole process that is necessary to reach the required satisfaction to feel successful.
What, to me, reinforces my conviction that success and happiness go in parallel is that you can write the same paragraph above, just by replacing success by happiness and the text will make just as much sense.
It is quite difficult to try to see a relation of cause and effect between the two concepts. Indeed, if you are not happy, can you feel successful? In the same line of thought, can you feel happy if you are not successful? You probably cannot.
Next to engaging in activities that match your values and working on bringing them to completion, a very important aspect for both success and happiness is to get others involved as well. Never hesitate to ask for help, for support and for feedback. You will never have enough of those. Other people’s input is very valuable to stay motivated and determined, as well as to avoid losing track.
A great way of increasing your level of happiness and success in life is to first envision what the ideal world would be. What would you do if you were the one who could make things “perfect” for yourself? Once you have defined this ideal world, you can start developing your own plan. Although in some cases, a drastic change could work, I would recommend having a step-by-step approach, as a drastic change all of a sudden could bring a lot of uncertainty and chances of failure that not everyone can handle. Set your targets to go from point A (where you are today) to point B (your ideal world). Define each step clearly and set realistic and rigorous timelines to this plan. Timelines are quite important because they will force you to keep taking action. Not doing so will always end up in inaction, because we are all very good and finding excuses to postpone what we prefer not to do. Another important part in the execution of this plan is to designate someone (friend, coach, family member, etc…) to remind you, to enforce these timelines and if needed to reprimand you, because there again, if you can get away with procrastination, chances are that you will indeed.
To sum up, the way to happiness and success requires the following: build your life around your values and choose the environment in which they can flourish. Have a plan to improve your level of fulfillment. Share the enthusiasm with others. Celebrate every success along the way. Do not forget to ask for assistance to make sure that you will not divert and give up on your plan.
This last point is actually quite important: many people feel unhappy because they have given up on their dreams.

Copyright 2009 The Happy Future Group Consulting Ltd.