Surround yourself with people who engage in high-quality dialogue. Listen to conversations that you’d want to partake in someday.
Avoid complainers, harmful speech, and gossip. If you don’t heed that advice, you’ll quickly begin to complain, harm, and participate in gossip. The voices you listen to must be educated (not necessarily in an institution), they must be problem-solvers, and they must be well-tempered, among other things. More and more, your voice will reflect what you hear.