What does traction look like Or Know When to Fold em

From Justin Jackson:

What does traction look like? Early on, you can evaluate your idea's potential by looking at:

Seth Godwin talks about this same subject in The Dip. It's a hard call. Most of the success I'm seeing now was sowed by almost 9 years doing something different and 2 years of almost tears as I wondered how I wouldn't fail my family financially.

Even thinking about that financial trouble now makes me almost cry.