I don't know why my hands shiver everytime i hold something. i'm just 19. what is the reason behind this?

Tremor: Heredofamilial tremors are not rare, and usually occur later in life, but you may have this problem early. Elevated thyroid activity and certain medications may also cause this sustention tremor. Coffee and emotional stress can increase, but relaxation and alcohol, or marijuana may calm it down. Your doctor can help

Essential tremor: or familial tremor occurs at rest or with sustained positions. It often is dampened by alcohol use (used as a diagnostic test or treatment in the past) Exaggerated physiologic tremor can occur under many conditions (holding something a bit heavy) and is not usually a serious matter. Hyperthyroidism can give you a fine tremor. If you are bothered by the tremor, see a doctor (neurologist)

Intention tremor: Although a benign essential tremor rarely can occur at rest it mostly occurs when lifting objects. Trying to use a spoon to have soup is tough especially if people are watching. Parkinson's disease is a resting tremor. Often a person will be seen to have "pill rolling" with the first and second fingers while the hand is resting. If needed a beta blocker can often quiet the essential tremor.