To not be cut out for something

If you're not cut out for something, it means that you don't have the ability or willingness to do it or be it.

For example, I'm not cut out to be a surgeon, or any kind of doctor. The sight of blood and needles makes me feel faint!

I'm also not cut out to be an engineer or a financial analyst, because my math skills aren't strong enough.

I'm not cut out for mountain climbing or skiing, because my knees are not good.

What about you? What aren't you cut out for?