Most facilities encourage or demand that inmates work or pursue an education. Even if someone is, G-d forbid, serving a life sentence, it is important to work. Every human being needs their self esteem. By working, they are contributing to their self-esteem.
Some inmates look for ways to avoid working.
On the other hand, some inmates look forward to going to their jobs. It gives them a feeling of accomplishment. Many inmates have learned new skills whilst incarcerated. It also makes the time spent behind bars go that much faster. As the saying goes, a watched pot does not boil.