I can't emphasize enough the importance of breaking in your boots as early as possible and getting yourself some quality socks.
On one of the first days after I checked on board with the Marine Infantry as a GMO, my battalion did a "boots and utes" run. An 8-mile run. I'm an excellent runner, but I was totally unprepared for a boots and utes run. In my mind, boots are made for hiking. Not jogging. That's what running shoes are designed for. But these are Marines I'm talking about. If there's a more macho way to do something, that's they way they're going to do it--even if it's completely stupid.
So, anyway, I was in the midst of this ******ed boots and utes run. My boots were brand spanking new plus I was wearing some cheap-arse dollar store cotton socks. Not a good combo to go running with. After mile 4 or 5, I could tell some serious blisters were developing. By mile 6, I was in serious agony--major stinging pains as I could feel the blisters ripping open with every stride. To my disfortune, I was running in the front of the battalion alongside all the Marine officers. These guys' testosterone is off the charts. Being the doc among the Marine officers is sometimes like a weird MTV reality show, like being a nerd sent to live in a house full of football players and ultimate fighters. It was made even worse since I was the new guy trying to fit into this veritable wolf pack. So the last thing I wanted to do was look like a complete puss, not only because I was the new guy--but because they already think all the Navy docs are totally soft, so I wasn't about to let them have the satisfaction of fullfilling that stereotype. So I did my best to stifle the pain and focus on detatching my mind from my body and going to my "happy place."
The last few miles were excruciating, but I was able to finish the run without betraying the fact that on the inside I was crying like a 6 year old girl. My feet were screaming in pain and it took every ounce of strength I had not to hobble around like an old beaten mule. Can't let the wolf pack see me be weak! Probably more than half the battalion didn't even finish the run (a lot of Marines were in surprisingly bad shape--many were already puking by mile 3--this surprised me initially but over the years I observed that a not insignificant portion of the enlisted Marines are fat lazy turds--though most are tough as hell). So, anyhow, I was proud of myself for finishing and feeling elated that the hellish nightmare run was over. . . . Or so I thought. Right after dismissing the enlisted guys, the battalion CO announced he was taking all the officers for an additional 5 miles. I think a part of my soul died when he announced that.
After a few miles into the officer-only run, I think so many pain endorphins had kicked in that I actually became pretty numb, so the final few miles were tolerable. By the end, I'd hung with the best of those Marine officers and even left a few sucking wind behind me. But when that run was over, finally over, and I got back to the Aid Station, I pulled off my boots. It was distusting. My socks were competely soaked in blood. My feet were destroyed. You'd think I'd just been pulled out of the ocean after a shark attack. The next day and for almost two weeks afterwards, my feet were so torn up and mangled that I couldn't bear the pain of wearing a shoe, let alone those effing boots. So I had to wear my cammies with flip flops on my feet. Ultimately, that's how I earned my call sign. Tenderfoot.
Thus, the morale of the story. Break in your boots early. Buy quality socks.