Do it

Yes, but ....

A good translation need not match the words exactly: what's wanted is a natural expression that matches the putative situation that gave rise to the original. (He said sententiously.)

I might say, "Do it--to whatever degree that circumstances allow"; but no matter what I do with "selon les possibilités," I get something that seems unnatural when conjoined with "Do it."

What I'm thinking is that "it" must be somewhat complex and nuanced to be properly modified by "according to the possibilities"; so that "doing it" or "doing it up brown" would amount to doing several things--only some of which are certain to be possible.

Now "whatever can be done" is supposed to refer to the subset of "it" that is possible.

What about "Do as much of it as possible" or--to my ears more natural--"Get as much of it done as you can"?

"Do whatever can be done" changed to "Get as much of it done as possible."

« selon les possibilités » can mean that, but can also mean that you may do it according to the means, meaning that you may use different methods in order to do it...so it's not only quantitative but also qualitative...

"Get as much of it done as possible" changed to "Do it any way you can" to better match "do it,"
which has pride of place.