That/Failing

[Volcano1985]

You ought to do just what I have done, determining, as I did, that whatever else had to be done afterward I would do with all my might, or make a better man of myself while failing.

Could please explain the bold parts?

[Soup]

You ought to do just what I have done, having determined/determining, as I did, (that) whatever else had to be done afterward I would do with all my might, or make a better man of myself while failing to do with all my might whatever else had to be done afterwards.

Note, determining is shorter way to say having determined which in turn is a shorter way of saying I determined.

Note also, that is optional. It doesn't contribute any meaning:

... having determined (that) whatever else ...
... determining (that) whatever else ...