But Where On The Shaft?

Drove through the snowstorm last night fine.  Not optimal, but fine.

But it was snowing.  Two or three inches, depending.  I could break out the snowplow, but I'm still afraid it won't work, and the relatively paltry amount of snow gives me a good excuse to keep it in the garage.

Instead, this is a good time to use what The Wirecutter called The Best Snow Shovel.  The site also recommends that I buy this particular second handle which I can attach to this ergonomically-friendly shovel because it lessens the strain on my back.

So I did, even though I haven't even attached it yet, let alone used it.  One problem: I have no clue where on the shaft to attach it.  The Wirecutter says two-thirds down; another says the best thing about the handle is that you can attach it where it best fits you, your height and the lengths of your arms.  So ... where is it best for me?

I don't mean to be a dunderhead about this, but I don't know where along the shaft of the shovel I should attach the ergonomic handle.  And "what works best for you," frankly, doesn't help me, because I don't know what's best for me!  Could somebody please tell me what's best for me!

Argh!  See, my ideal plan was to wake up this morning before football (I happened to wake up a bit past 9) to shovel and then just relax and watch the games and stay in all night.  But I've been paralyzed by not being able to find online a website that can tell me, just me, where I should put this handle.  I ... I don't know if I can shovel without knowing this piece of information.  And the games are about to start, so I don't know if I'll even care.

No, at some point this afternoon I'll forget about watching football because I have to shovel.  Maybe I'll do it this later this afternoon, while the Vikings are getting their asses kicked by the Patriots.  But ... I would think that there would be something on the Internet that can tell me this piece of information, and there isn't.  Why the heck not?