The fact that most hiring managers in average don't spend more than ten seconds on reviewing a resume says a lot about how they approach cover letters. So if you are happy about your 2 or even 3 page cover letter, you might want to re-do the document because your message will likely be never read (or lost in the rattling of your accomplishments and qualifications). Cover letters, just like resumes, rarely should be over 1 page. Even if you are qualified for the position, it is very unlikely the employer will look beyond page 1 anyway. If you have already written a cover letter and it is longer than one page, then you should consider the recommendations provided below.
How to Shorten a Lengthy Cover Letter
Many job seekers believe that a cover letter is meant to summarize the information provided in the resume. What they forget is that a cover letter is an addition, not a summary. It is important that both application documents match up with the job requirements but it also important that they don't repeat each other (why would one create two separate documents to say one thing?). A cover letter is mean to fill in the gaps a resume can't touch upon due to its nature and format. The accompanying letter is a great opportunity to share more than a bunch of titles and skills but rather to tell your career story.
Keep Your Opening Short. It’s usually smart to start your cover letter with an interesting line or a personal anecdote to get the reader engaged from the get-go. That being said, be mindful of how long this drags on for—if you spend half of your cover letter introducing yourself in the style of The Bachelor, or take an entire paragraph to talk about the one trip that made you realize you wanted to become an engineer, the excitement will get lost—leaving you no room to talk about why you’d actually be great for the job. When starting out, stick to one or two sentences about who you are, then move on to the more important stuff. 
Find the Fluff. I’d bet that a decent amount of your cover letter is fluff that’s trying to sound impressive, yet lacks specifics. If you’re using typical lines like “I would be honored to work for [company] because…” or “I believe I am qualified for this role because…,” cut them out and start immediately with the “why.”
Consider Your Adjectives and Adverbs. Print out your cover letter. (you’re going to have to find a printer.) Circle all the adjectives and adverbs. Now take a look at any sentence with more than one and cut it down to just one. For example: Do you have to be a “very passionate and focused learner,” or can you just be a “passionate learner?” Did you “institute an immense amount of truly important changes” or did you just “institute important changes?” Yes, sometimes long, elaborate sentences make you seem smarter. But, more often than not, they make your message harder to understand. And wouldn’t you rather your experiences speak for themselves than get overshadowed by your flowery, overly enthusiastic language?
Choose Two Examples to Make Your Point—and No More. There’s nothing more exciting than reading a job description and realizing, I have all of these qualities! Score! The thing is, as perfect as you are for the role, you unfortunately have to pick and choose what you talk about. And by this, I mean take your two best examples, the ones you’re proudest of, and focus on those. Explain them enough so that there’s context behind your resume, but not so much that you’re going off track from what they’re looking for. It may seem intimidating to select one experience over the other, especially if you have a wealth of knowledge, but remember that your resume still holds that information.
Consider your cover letter your last chance to say hey, I know you can see how awesome I am for this role, but here’s a little extra that makes me even more awesome.
