Ashwagandha

Ashwagandha is a classic adaptogen of Ayurveda (traditional Indian medicine).  It is commonly used to support conditions of weakness.  It can benefit the immune system and hormone levels which support a healthy stress response.  It is also proven to improve physical attributes such as strength and endurance.  Ashwagandha is a getting more attention than ever before as it shows reliable effectiveness yet it is very safe and gentle.

Ashwagandha in the treatment of anxiety:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270108/

Ashwagandha improves athletic endurance:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3545242/

An overview of Ashwagandha:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3252722/