Don't do it because it's the norm

Generally, a good advice.
I applied it with sports... when I was a kid I would skip sports classes, didn't think they could help in any way, didn't want to spend time on that. In fact, I did that up until I finished college.
Only when it wasn't mandatory I started considering it. I started learning to run at about 20. Close to zero experience, besides running to catch a train and having a nosebleed. I literally couldn't run more than 10 minutes without taking a breathe.

Find your own pace

While learning how to keep a pace and get a sense of what long-distance running is about, I recommend that you have someone that can guide you.

After that, running with someone else may boost your performance, but at the end of the day your true ability is how you do when running alone.

It sometimes happens that running at someone else's pace tires you, even if it's a lower pace.

Preparation is important

It is, quite frankly, the most important.

Not only preparation is important

Weather is important.
Race organization is important.
State of mind is critical.

But, you can't control any of these, so don't stress about it.

No pain, no gain

The most difficult was learning how to run up to 9 miles... like, without stopping. I mostly tried outperforming myself in the weekend, and sometimes I couldn't even run the previous week's mileage. Or sometimes I'd injure myself and couldn't do any sports for a week. But in time, strength builds up.

It's like learning how to ride a bike

Once you've trained and it's in your system, you won't lose it easily.
For the first half-marathon I trained for more than 6 months (and I'm not counting the timeframe when I literally didn't know how to run). I followed a schedule, gradually increasing the miles I ran. I realized that my metabolism needs food 2 hours prior to running, so I had to wake up early to be able to run at 9am. And many others.

I only ran 4 miles prior to the second half-marathon (which was 6 months distance away from the first)... and even got a better time.

Discipline

The discipline of training, and continually outperforming.

Now... I should admit I have written this blog post for myself, as I haven't been running for more than half an year.
I'm making it a 15th of January resolution :)