Using Nervine Herbs Appropriately

I'm a 28 year old male. I have been taking HVP – Hops, Valerian and Passionflower. It says the proprietary blend is 780mg. I absolutely love the way it makes me feel!!! I'm really wondering if I have been stressed out my whole life and just didn't realize it. Once in a while I will take a capsule or two of Kava Kava.
My question is, how long can I take these herbs on a daily basis? And how much is too much. I also was wondering if maybe I could switch back and forth to St. John's Wort or any of the other herbs that help with the nervous system. I do not want to abuse these herbs and was wondering if you could give me some suggestions.

To herbs appropriately, it is essential to look at the whole person in order to identify causes of specific symptoms. Diet and lifestyle play an important part in physical and emotional well being. Foods high in vitamins B (whole grains, nuts, seeds, green vegetables) and C (citrus fruits) nourish the nervous system. The nervous system needs an environment of emotional support, and activities that fulfill the heart's desires.
Herbs can help the nervous system while the individual takes the time to identify and re-evaluate causes of nervous stress, and to choose relaxation exercises that are appropriate and enjoyable.
I suggest that you work on identifying means of nervous system support in your diet and lifestyle so that you can eventually eliminate the need for herbs.