What does one do in Prison?
Most facilities encourage or demand that inmates work or pursue an education. Doing this enables an inmate to earn "good time" and so be eligible for earlier release. 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. If all one is doing is thinking about where they are, the time seems to take forever.
In the Federal system, if you were convicted of a crime that was committed after November 1987, there is no parole. There are a number of inmates who have life sentences and so, unless they win an appeal, they are incarcerated for the rest of their lives. Nevertheless, they go on. They utilize their time to further their education and knowledge.
After work, many places offer various activities. At the very least, one should utilize this time for self-improvement. One should ask their friends and family members to send them reading material about topics in which they are interested. Again, each facility has different procedures about how to send books, magazines, and newspapers. Again, by doing something meaningful in prison, time goes by much faster , and can be somewhat constructive.