I'd go for "it".
My version is:
"I love going for long walks on Sundays because it makes me feel so close to nature."
Please read the sentence below.
(It's rather a weird sentence, but it will shed some light on your query.)
"I love breaking windows. It makes me excited."
What makes the speaker excited?
Breaking windows(='it', not 'they') makes him/her excited, doesn't it?
I hope you'll understand what I mean.
Student or Learner