M&K wrote:
I have a young maple that I am planning on pruning this fall. The
lower branches are simply too low and I have to almost kneel when
mowing around the tree.

The rest of the branches seem almost too long and seem to be sagging,
so I was considering trimming them back so there wasn't as much of a
load.

Thoughts?

Don't be shy. Any plant responds well to judicious pruning, and when
they're growing up is most important. You want to make the tree find a
compatible shape for the location and purpose it serves.

Low branches are obviously going to be in the way, so trim them back
right up to where the tree begins to crown out. Eventually it will grow
up several stories, so it won't need those. Look inside and decide
which major branches are going to be the tree's lifetime structure.
Branches which sag are growing fast to get out of the tree's own shade
to sunlight, and will always be weak. Expect to get rid of these. It
isn't a "load" issue, it's that the tree already needs thinning in its
upper reaches.

You don't need to do this all at once, but over a period of years,
you'll need to do a little of this at *least* once a year.