When we are looking for fulfillment in the world body mind, we are often disappointed as we are trying to find peace and happiness in the impermanent.
We may find a certain pleasure, a fleeting sensation of happiness, and since it is dependent on an object, we feel the tension of needing to maintain this object. Thus the worry and concern.
The effect of any cause is fleeting. Only your true nature, which is the reality of being/awareness is eternal.
Painting by Fernando Osorio