I’ve written about reading your writing out loud to make sure your voice is coming through.
Another helpful technique is to record yourself talking.
If you’re working on website copy, simulate a conversation with your ideal client about who you are and how you can help them.
If you’re working on a blog post, give a mini-lecture about a topic within your area of expertise.
Use the free Voice Memo app on your phone and transcribe the recording or use a tool like Otter to transcribe the audio for you.
Once you have a transcription, then all you need to do is clean it up.