My mic is also sensitive. I've experimented a bit and there are some things I've found that help generate quieter measurements:
- Mind your footsteps: My mic picks up on my footsteps if I'm not mindful of them. Stepping on dried leaves or twigs, kicking a rock, a mistep on an uneven sidewalk, etc. Even the pair of shoes I wear - some pairs are quieter than others
- Empty pockets are best: keys, coins, reading glasses, etc jangling in the pockets are picked up in my mic
- How you hold the phone: If you hold the phone and your letting your arm swing freely, air flow over the phone (mic) is like situating the mic in front of a fan. Holding the phone steady, flat and face up seems to work best for me in getting quiet recordings.
Terrain: walking in grass is louder than walking on pavement.
When you start paying attention to the noise meter and trying to make quiet recordings, you really become aware of the ambient noises: traffic (even from busy roads far away), birds, crickets, air conditioners, water fountains, sprinklers, wind, etc.