How many anyone have you ever seen faint while walking when it was hot?
I have seen people faint while they were standing still from the heat. I have also been hiking, Boy Scouts and otherwise, and seen people nearly pass out from the heat because they weren't conditioned enough for it or hadn't been drinking enough.
But since D&C 89 does not say "obey and it won't be hot outside," this is all quite irrelevant.
Do you know anyone who walks and faints?
Yes. People who haven't been eating right and exercising sometimes have difficulty walking around. I know people I've been with in the downtown areas of different cities who have needed to sit and rest after walking just a few blocks.
D&C 89 was also written in a time when walking was a normal way to go even long distances. Many of the Mormon pioneers who came to Utah a few years after D&C 89 was "revealed" walked, either on their own or pulling handcarts.
The fact is that if a person actually followed the dietary guidelines of the Word of Wisdom it would greatly benefit their overall health---and I mean what it actually says (beer is permissible, and so is wine if you make it yourself). However, the modern LDS Church does not enforce what the Word of Wisdom says. It enforces the temperance movement favored by Heber J. Grant.
If you wanted to talk about whether the Word of Wisdom was a revelation or simply adopting ideas about dietary health that were in circulation during Joseph Smith's time, that would be one thing. Or if you wanted to discuss the circumstances of how the LDS Church decided the Word of Wisdom was a commandment (and even then only certain parts), that would also perhaps be some substantive issue. Instead, you are once again grasping for anything you can complain about in another pointless drive-by post that has no apparent factual basis.