I is one of those overused words. When I taught literary analytical writing, I'd often try to get students to reduce or eliminate the I from their writing. It's not a bad practice for most writing, even fiction. If you can find a way, even when using first person, to remove I in the sentence, you'll find your writing and descriptions become stronger.
A quick, useful exercise is to write a passage-try four hundred words-without one use of the pronoun I, me myself, mine, my. It's a challenge, but you're up for it aren't you? Remember, the key is to get your character across without the self-reference.
You may find your writing stilted at first, as it's an effort to word things without the I, but it's a good exercise. Of course, you wouldn't write a whole piece this way, it ends up being clunky and forced, but to find ways of stating your point without I invigorates your description.
By the way, this is one of those things that is definitely not meant to be a "rule" of any kind, merely a heads up on one way to add variety into your prose.
If you choose to do the exercise and wish to have some feedback, please leave it in the comments below or email me at firstname.lastname@example.org