Concreting is a very heavy, demanding trade.
You would need to be in incredibly good shape to do concreting work. It requires that you know all about reinforcing bars, rebars and how they all fit together. You also have to understand how concrete mixes and setting time for the concrete with the right movement.
Concreting is not for people who just want a job because it takes years of training and schooling before they can even get jobs as labors working on crews at the bottom of the company ladder!