What are some good natural supplies to improve brain functioning, helping with serotonin levels or mainly just adding overall feeling of wellbeing?

Brain function: You can never go wrong with just adding overall feeling of well being.

Regular exercise,: regular sleep habits, a good and balanced diet, satisfying job, and home life, fun hobbies, learning new things every day and waking up expecting it to be a good day no matter how yesterday went. No specific food or supplement will substitute for that.

Exercise!: Exercise and healthy eating are probably the best way to improve sense of well being. Brain functioning improves mostly by using it! Gingko biloba may have some positive effects. If you are having mild depressive symptoms you can try Sam-e. Also, be sure you are getting enough good quality sleep.