Tremor is a normal physiologic reaction to anxiety or stress, but it is not normal to have a tremor when performing typical daily activities.
People who develop a tremor while eating, drinking, writing or doing other common activities may have a movement disorder called Essential Tremor. This is actually the most common movement disorder, and can affect up to 4% of people over age 40. People who have this disorder can take medications to help minimize the tremor, but they don't often reduce the tremor by more than about half. Deep brain stimulation (DBS) is an excellent treatment option for people with severe tremor, and can nearly eliminate the tremor in many patients. Many patients aren't sure when their tremor is severe enough to warrant surgery, and much of our conversation in the office is to help answer this question.
There is no one answer that is right for everyone, but for me it has to do with how well someone is actually doing in their daily life: