One of the most consistent factors that is common amongst successful language learners I know is an attitude of boldness. This cannot be overstated.

Language learning is an inherently scary endeavor. It forces you to show your vulnerabilities to other people, who will be able to pick out every mistake you make. As such, lots of language learners (myself included) have a natural tendency to adopt an attitude of timidness. I know speaking is one of the most important aspects of language learning, but as soon as I get the opportunity to actually speak to someone, I turn into a timid turtle. It feels a lot safer to hide in my shell than to actually stick my neck out and practice the language I've been studying.

The good news is that you can ACTIVELY PRACTICE developing an attitude of boldness. I'm not saying change who you are. Some of us are natural introverts, and there is nothing wrong with that. If that is you, don't try to spend every hour of the day becoming more outspoken. That is exhausting and will lead to burnout. Instead, find a few short time slots throughout the week to actively and deliberately practice overcoming your apprehension. Little by little, you can drop that attitude of timidness, and switch into Bold Language Learner mode whenever the moment is right. And don't worry. You can always switch back to introvert mode when your conversation practice is over.