syntax of "坚持不了"

[jostan_usa]

A friend wrote to me: 想是有这样想，但就是坚持不了！

All the machine translations put a negative spin on "坚持不了" -- e.g.

"cannot persist" or "do not continue".

MDBG translates "不了" as "bu liao = unable to, without end" -- which seem contradictory.

From the context of her remarks, I feel like my friend is saying she will "persist until the very end", but this is a reversal of the syntax indicated by the web results. Here is the full context:

多买点有关的书籍，要多学习！

我觉得我自己好懒有时候，想是有这样想，但就是坚持不了！

My translation:

I bought some more relevant books, want to learn more!

I consider myself so lazy sometimes, I want to believe I can do it, still I'm definitely committed until the end!

The web translations would imply that she "cannot persist" -- is ready to give up.

Which is correct, and why? Is there a rule or guideline involved here?

[imron]

The online translations are correct. It means she doesn't have the willpower to stick at it, even though she might want to.

想是有这样想，

Here she is not saying "I believe I can do it", but rather "in an ideal world, this is what I'd like to do"

但就是坚持不了！

but, I'm unable (e.g. don't have the discipline/willpower/strength) to keep at it.

[renzhe]

不了 is an important grammatical construct, have a look here for some background.

Essentially, it means "cannot".

[yan420honggg]

Verb + 不了 = unable to + Verb

Your friend means she has thoughts to do sth,but it's tough,she can't do it for a long time.