I've been taking for about a year. My older sister started before that. I used to have extreme anxiety. After taking my first few days, I had a major city-wide event I was in charge of. I left in the morning without the anxiety and felt in control and confident all day. I don't think 5 htp MADE me confident. What happened was that my anxiety was out of the way which allowed me to have confidence in all the planning and work I'd put in to make an awesome event. When there was a glitch, I wasn't destroyed by it.
I have since started taking 5 days a week with 2 days off (weekends for me). The natural store said you don't want to shut your system down from having its own ability to create it's needs. I believe my sisters (there are more of us but only two of us take 5 htp) have low serotonin levels. There might be other ways to boost the levels.
I also work on nutrition, exercise, calming strategies, silence (I'm Quaker so this is similar to meditation), and creating fun.