There are almost 7 million adult learners in the United States alone. Anyone in school over the age of 25 is considered an adult learners. Jini Thornton says that the very first step is to figure out your why. Next you want to contact your local school and see what programs that they have available.
If you’re retired don’t let that stop you from furthering your education. Often times there are specific programs available to people over 50, like auditing. People over 50 can audit a class meaning that they can take the class to learn the skills for free but won’t receive a grade for that class.