PS afterthought - Do a Google search for "middle voice". In 'let your feelings show' the 'object' of 'show' is 'feelings'; or it's
subject is 'feelings', and what they show is their existence. Hmm...

not an easy concept to explain...
And an afterthought on the use of 'so' instead of anything clearer especially among song-writers:
'So' gives scope for lots of rhymes. Just using the first 5 initials there are:
ago
although
bow
beau
crow
doe
dough
ego ...
Whereas 'so hard' has very few (and not very useful ones) - card chard guard lard nard and simple past forms of some (often fairly obscure0 verbs - char, mar.
And 'so much' is only useful for songs about rabbits (hutch) or chickens (clutch)...
I loved you so strenuously
But you reciprocated tenuously... [Doesn't really work

]
b