travel and rhum

I've just recently started hiking for the first time in like 20 years, but I've noticed a lot of people I see on the trails only carry 1 bottle of water and have no first-aid kits handy. I'm a stickler for preparation so I bring snacks, plenty of water (I go through about a 2 liter reservoir each hike depending on length and carry 2 extra bottles), a basic first-aid kit, and an IFAK (geared toward serious bleeding wounds). I generally have enough to share if needed and my backpack alone weighs like 16 pounds (almost all Cliff Bars lol).

What are some of the biggest mistakes you see fellow hikers making when they hit the trails?

I know there's a lot of factors like difficulty, how many days you go, and how much you do, but just in general. The only thing I know is you build endurance but I don't know what physical changes you'll see. Hopefully loss of fat and looking leaner.