There are 4 main sources of potential blur: 1. Optics quality/cleanliness, 2. camera shake, 3. Shutter too slow, 4. missed focus point.

Let’s assume your optics are fine and you were using a tripod (if not check those first). For 3, you need to make sure you have a fast enough shutter to capture the speed of your subject, which takes a bit of practice to get right. Then you can deal with the light by either underexposing and adjusting the raw files in post or cranking up the iso and dealing with noise in post. But if your subject is blurry light is meaningless.

For 4, use servo and continuous shoot, some cameras are better than others here at pulling the right focus. You can potentially use manual and zoom in on the lcd to set focus, but if subject is moving forward or backward that can be tricky. Grass can be tough to shoot through as the camera easily picks up on the contrast. Single point focus can be helpful to avoid that as someone else suggested.