There are three forms of Suffering. Ordinary suffering (Dukkha-dukkha) such as physical and mental Suffering associated with birth, growing old, illness and dying.
Suffering due to change (Viparinama-dukkha). Anxiety and stress is caused by the longing to hold on or attach to things that are subject to change. And as everything in life changes, as everything comes and goes, there is a lot of Suffering. The third form is Suffering from conditioned states (samkhara-dukkha). As everything is impermanent or transformative all forms that exist never live up to our (fixed) expectations. The force of Ego is what fuels all Unwholesome mind activity and hence is the root cause of all resistance and Suffering.