A few things I've learned

1. It really does get easier. 5K used to seem like such a long distance, and now I'm running 20K on Saturdays. It's still tough, and I'm still slow, but it's doable. And not only am I running longer distances, I'm also running faster.
2. Listen to your body. This is important for staying injury-free, for figuring out your pace, for food and hydration habits, everything. Running is an individual sport, and only you know how best to run for you.
3. That being said... You can push through the wall. Some days you feel rough and every step is a struggle, and some days you feel like you can go for miles and miles. The important thing is to try and go further than you think you can on those bad days -- because chances are it'll get better and you'll be amazed at doing what you thought you couldn't.
4. Shoes are important. I've been running on and off, starting and stopping Couch to 5K programs for the past few years, but only really started training in January. I've probably had the same running shoes the whole time, until I got my new Asics last month. What a difference! Don't be like me, kids, get good shoes and replace them when necessary.
5. Goals are important. When I signed up for the half, I hadn't even run 10K in one go. But having something to train for and work towards really keeps you focused and ensures you get your shoes on and your butt on the road. Until I started training, I had no idea really what my body could do. I had never given it a reason to do anything. Now I know what I'm capable of, what I can improve on, and chances are I'll probably sign up for the Scotiabank Vancouver Half-Marathon again next year so I can keep myself going.