I feel that my research makes sense, when I can translate my own results into clinical practice (as it is with my paper about prediction of blood loss in laparoscopic myomectomy) and/or when I can translate my clinical practice into reliable and generalizable results (as it was with my paper about hemostatic matrix). Furthermore I still did not give up my belief in case reports - true stories from which you can learn (as in real clinic) or exceptional clinical cases which build the history of medicine.
The happiness comes out when your soul is present in the research. The research which you are doing does not gives you boredom after you are deeply into it, but everyday when you start your work, it inspires you that i have a lot more interesting to find. Since, it is a process of self learning and exploring, you need to have you present there, with your heart, mind and soul.
When I see that my research results have been published and my knowledge have been enriched it is the joyful part of my career. when I can realize that my research can benefit everyone.