I confirmed, in the middle of a field, that I indeed did need a new battery.
Been there, done that.....not fun! How far did you have to walk?
I got caught in a sudden rain storm several years ago on a large property I was mowing. I had just checked the phone radar and nothing there, but only takes minutes for storms to appear here in the summer. Anyhow, I backed up under the edge of a tree to fend off the driving rain that was soaking me even though I had a canopy. Shut the tractor off and waited about 10 minutes for it to pass. Turned the key to head in to the truck and no go.....dead battery. Great! No choice but to walk the 1/2 mile back to the truck and come back to get the dead battery. Brought the truck back and got out to pull the battery and realized I'd just run over the left piece of the hood which was propped up against the tractor tire, but had fallen down. Great! At this point I was getting just a touch aggravated. Pulled the battery and headed out for the day. On the way home I stopped at the battery store and got a new one to install the next day.
Got back to the job the next day, put the battery in, started to bolt it down and.........wait for it..............wrong battery! Another trip back to the battery store 30 miles away. In defense, the guy said "that's what's supposed to be in it". So I told him to measure the old battery and low and behold it was NOT the right one.
Luckily from that point on things got better. Any time I think I'm having a bad day I go back to that one and think....things really ain't that bad!