While stress is usually caused by something external, anxiety is a fear of the future, and doesn't go once the trigger has gone. Although humans are hardwired for some anxiety, the problem is our anxiety levels can become locked on high for too long.
Different factors contribute to developing clinical anxiety. About 30% is genetic, the rest is environmental. Different conditions have anxiety at the root cause including:
Obsessive compulsive disorder
Can consist of high levels of sadness, low self worth, hopelessness, helplessness, low motivation, a lack of energy, withdrawal from friends and family, poor sleep, and thoughts of self harm and suicide. It is important to realise this is a syndrome and is highly treatable.
Psychological therapy is a wonderful treatment for anxiety, depression and stress. Many clients who attend therapy at the Engel Clinic report improvement in their first two sessions.