To begin, I must confess: I don't have a gym bag because I never go to the gym. I do, however, have a few items I like to have at the ready for a good long run:
1. A Buff
I love Buffs. Alex gets a ton of these for free and I bought a smaller headband size last summer. I sweat a lot and my hair is really thick, so I need something that will stay on and soak up sweat. I've been using these regularly since October. I'm curious to see how they'll be in the summer, but so far I love them. I can use them as a headband, headwrap, or neck warmer.
2. My Garmin
I've only had my Forerunner 10 since December, but I'm so happy I don't have to lug my phone around with me on every run. It syncs with Map My Run so I can still keep my account up-to-date.
3. Good, non cotton socks
I've made the mistake of running in normal socks a few times and I've paid the price. I love my Nike Dri-Fits (from Kohl's) or the more expensive alternative, Balega. Prior to Christmas, I owned one pair of Balegas. Thanks to my mom and step dad (and a free pair in a race swag bag) I have 6 pairs.
4. Water + Nutrition
I carry a handheld water bottle on all long runs. I have two sizes depending on the length of the run and each has a pocket where I carry my nutrition. Last year I swore by chews, but when they didn't cut it for me on my first trail run, I went back to gels. I believe my decision was less than scientific: I went out of town for work before a half marathon and came home to discover I didn't have any chews, so I grabbed a Clif Shot. I'm pretty sure it was Alex's because it was Espresso (which I would never buy)... but I loved it.
5. Road ID
When I'm going on a run around town, I like to have my Road ID bracelet just in case something happens. I especially like to wear it if I'm not carrying my phone and during races. Road ID is a great company and I also purchased a set of reflective wrist bands that I wear on after work runs in the winter.