I am forty years old and want to learn a skill to find a job. What should I study?
If you are 40 years old, you can learn a snack technique, open a small shop yourself and invest in it, with low cost and high profit. Most snacks can be finished by one person.
Or learn from the chef, who is not a career of eating youth food. It doesn't matter if you are older, and the salary of chefs is higher now.