In the Bible, the word “self-control” is used to talk about people controlling the things they do. That is, they stop themselves from sinning. They choose not to do something wrong that they want to do. Self-control is a fruit of the Holy Spirit (see: Galatians 5:22-23). God helps people to have self-control.
Self-indulgence is the opposite of self-control (see: Matthew 23:25). When someone acts with self-indulgence, they sin because they want to sin.
Paul talked about an athlete having self-control. Athletes train their bodies to be able to win a competition. They also avoid anything that may harm their bodies and cause them not to be able to win (see: 1 Corinthians 9:24-25). Paul talked about athletes in order to talk about how he uses self-control so that he may receive a reward from God (see: 1 Corinthians 9:26-27).
The Bible commands that Christians use self-control (see: 1 Timothy 2:9; Titus 1:8; 2:12; 2 Peter 1:6).