Lots of patients complain about memory problems when they come to my clinic. Most of the time it is a problem that has no clear onset and the problems often pertain to issues in daily life such as "I cannot seem to remember where i kept my keys" or "I have difficulty remembering names."
Most of the time if it is a new problem, the most common issues to rule out are recent stresses and sleep deprivation, new medications and worsening of other health issues and vitamin deficiencies. I often tell my patients that in order to make memory one needs to be able to concentrate and process information so that our brain can consolidate/store it.
Our brain is like a muscle and, like with all muscles, exercise makes its stronger. I tell my patients that eating healthy, getting rest and doing brain exercises with tools such as a crossword puzzle would be immensely helpful in keeping one's mind sharp.