A lack of focus is not the same as simply not paying attention. You will notice that you are suffering from a lack of focus if you are starting to be easily distracted or are missing some of the finer details after having a conversation. Some of the additional signs of a lack of focus include not being able to complete projects and not listening well to others when in a conversation. Unlike people who are affected by ADHD, a lack of focus due to a lysine deficiency will be sudden in its development, which means that you should be able to notice that you aren't able to focus on things like you once were.Next