How can I stop controlling my breath when I meditate?

You're definitely not alone if you sometimes try to control your breathing while you meditate. It's really common. Often, as soon as we hear the instruction to breathe naturally, we instantly change the way we breathe! The instruction here is really just to be with the breath however it is, from moment to moment. So in one sense, even if you're manipulating the breath in some way, that's how the breath is in that moment, so you can simply bring your awareness to it. Being curious about the experience can also be helpful because it allows you to be open to the breath no matter what, whether shallow, tight, uncomfortable or anything else.

‍
If you keep having a hard time using the breath as the focus of your mindfulness meditation try changing your focus to sound or overall body sensations. When you work with sound as your primary focus you simply direct the attention to all the ambient sounds in your environment. There is no need to try to hear anything or to identify what it is you are hearing; just be aware of any sounds that come into your ears.

‍
If you work with the overall sensations of your body, be aware of what your body's feeling as you're sitting, laying, standing or walking. Notice the feeling of the whole body sitting, for example. See if you can become aware of any points of contact between your body and the chair or cushion you're sitting on and allow those sensations to be known.

‍
With either of these two options, the practice would be the same as it is when you use the breath as the primary focus. Every time you notice your mind has moved away from your focus, gently bring your attention back to either sounds or the body sensations. It is generally best to choose a primary focus at the start of a mindfulness meditation session and to stick with it throughout the session.

‍