Money and health are only a couple of potential concerns but are probably the two most important. Living in Mexico can help stretch that all mighty dollar. Look at the cost of living in Countries like the United States for example, you might consider working an additional number of years, or getting a job after you retire to help assure your retirement and keep up with the always increasing economy. As of now based on my current understanding of the Mexican Stock Market I can't recommend investing. However, a savvy investor may feel more comfortable in this venture.
Health can be a very important concern when approaching the retirement age.
High blood pressure and respiratory concerns effect many people. Living in High elevations may not be recommended because of the low oxygen levels. Living at or near sea level has been highly recommended by many doctors. Medical facilities exist in the Yucatan and Maya riviera. Medications are available in almost all major supermarkets and many pharmacies along the coast and as of today, you don't need a prescription to obtain the medications legally.