A farm listing is not a spa with cows. You will walk, lift, sweat, and then eat. If that sentence does not sound like a good day, pick a seated event.
Feet and skin
Boots or closed shoes you can ruin. Socks. Hat. Sunscreen you already tested on your face. Long sleeves beat heroic sunburn. Ask the host about snakes, dogs, or monsoon mud if the listing is quiet on it.
Pace
Match the host. If they are moving plants, you are moving plants. If they sit for tea, sit. Do not invent a workout. Do not lag so someone has to babysit you.
Food
Say allergies in the application, not at the table when lunch is already on the fire. Bring a snack if you get shaky. Do not expect a café menu.
When a farm day is live on experiences, apply only if you will still want it after you check the weather.