What does the Bible mean by temperance, and does it only refer to alcohol?
Temperance means maintaining balance in any area of life, not merely abstaining from alcohol. The context uses athletes who train for the mastery: they neither overeat for energy nor starve to lose weight, but keep their bodies disciplined and balanced. So temperance applies broadly to all things, including the spiritual race, for reward not salvation.
Les explains that Paul repeatedly uses the Olympic and Isthmian Games to illustrate the believer's life. The runners competed to win, so believers should run their spiritual race to obtain reward, not salvation, since the Corinthians are addressed as brethren. The athlete striving for mastery trained, neither eating everything for energy nor starving to carry less weight. The whole idea was temperance. Les says this does not refer only to alcohol or booze; the word temperate means that in any area of life you maintain a balance.
And every man that striveth for the mastery is temperate in all things. Now they do it to obtain a corruptible crown; but we an incorruptible.
More Questions
How does temperance apply to running the Christian life?
The Christian life works the same way as these examples: you don't go clear off to the right or clear off to the left, but you maintain that balance, being temperate in all things.