Giving Up or Giving in?

The pain hit like a pair of little knives, one for each side, and my legs went weak.
You never really know how you're going to feel in a 5K until you start, and Saturday was a perfect example. I felt great before the race, and I steamed to a 6:53 start for the first mile. That's a little fast, but given the way I'd been running lately, it wasn't going to kill me.
At least, I didn't think so. The pain got worse. And at that point, you have two options. The first is backing off a bit, trying to breathe through the hurt while keeping a good pace and suffering for 15 more minutes until you cross the line.
I've done that before. I did it this year, during the Bolder/Boulder 10K. I was proud after I finished with a personal best.
Only I didn't want to do that this time.
For some reason, my personal will had turned to Crisco, and so I chose option number two.
I quit.
I didn't stop, nor did I walk. But I stopped running hard. I essentially let my discomfort dictate the race, and three weeks after I finished with one of my best times ever, I finished with my worst time since I began running seriously three years ago.
I'm still not sure what went wrong. Maybe I did start too fast. Maybe I'm not as fast as I thought. Maybe I'm just exhausted. Maybe it's just all of it.
Since the twins were born, I was determined to push the exhaustion aside and keep living my life the way it should be lived. That meant I would continue to run, seriously, and climb mountains and watch a movie late into the night if that's what I wanted to do.
I made some concessions. I climb maybe three or four times a year now, a steep decline from what it once was, and that's OK. But I refused to make excuses. Everyone has things they deal with and continue to live their lives.
Yet lately either I'm getting weaker, or they're getting stronger. Regardless, I feel right now like I'm losing the battle.
It's taking its toll on me. And I'm allowing it to happen.
Why now? I have no idea. It might be that they're teething. Or that they're still not sleeping through the night. Or that Jayden has suddenly developed his 3-year-old personality, which seems to be equal parts stubbornness, sass and the word "no. Or maybe it's all of it and the ethanol in my tank is down to fumes.
But I am going to bed now at 10 p.m., after a bit of reading, writing or a smidge of online poker. I used to hate going to bed so early, when I could use the extra time staying up allowed. Now I'm simply too tired.
I will climb this year, but only two more times. I will race twice more, maybe only once more. And now, as Saturday's 5K shows, there's no guarantee that I'll be as tough as I should be.
Am I allowing myself to give in every once in a while, or am I just giving up? That's the debate that's circling through my head today.