<span>Mike joined the Army, and he became more disciplined during the training. -is the correct way to rewrite the run-on sentence.</span>
I definitely can't answer for your personality lol<span />
It looks good.
You did a nice job being descriptive and your grammar looks fine.
The reason for the cover letter<span> is to acquaint yourself with an association, show your enthusiasm for the organization or a particular opening, attract thoughtfulness regarding your resume</span>
