###Human: There is lack of concentration with negative thoughts. Why? ###Assistant: Hello. It is quite common for 18-year-olds to become stressed when preparing for school final and college entrance examinations. With appropriate care and encouragement, you can support your child to handle to stress appropriately. Kindly do not put too much pressure on him to study and excel. It can be counterproductive. If he is putting too much pressure on himself, it can lead to significant stress and affect his ability to do well in exams. Remind him that though exams are important, it is not a life or death situation. Continue to encourage and support him to do well but also tactfully advise him that there are multiple career options available. This can help him to relax and eventually help him to do better. It is good to know that he is eating and sleeping well. Encourage him to do atleast 30 minutes exercise or physical play daily. It is time well spent, it will sharpen his memory and reduce his stress levels. If stress continues to increase, it can lead on to depression, anxiety and related emotional and behavioural problems. Do not let exams to take over the family all the time. Have fun whenever possible. Remember a relaxed mind performs better.