What's the best job training field to study that has short class time with high pay in the field?

For someone not looking to go back to school for a long time, what's the best job field to study that is high in demand but will also pay a decent amount when you start working in that field?|||I would say working in the medical field, because people are always sick. Depending on where you live a Home Health Aide, is about 3 weeks of training. It allows you to have the flexibility to work 24 hours a day. Some agencies pay up to 17.00/hour. You have only one person to watch, so it not such a demanding position.