Like others have said, you have to practice to be able to do it. Part of the issue is building the muscle memory and dexterity in your mouth. Other people have already recommended shadowing, so just consider me seconding them.
If you’re ok with the older video and use of romaji, I recommend Let’s Learn Basic Japanese (on YouTube). The video series has ample practice for shadowing, has practice for producing sentences on your own, goes over the sound of each kana, and is all at native speed. If you can understand what your teachers say, then it should be a breeze to understand. Although if you’re not having any trouble with comprehension, you might already be beyond N5.