I'd add that the lines underscoring your sincerity, enthusiasm, and hard work might even backfire on you since admissions committes are generally looking for evidence a student can succeed, not just that they'll try really, really hard. No amount of enthusiasm and good intentions could make up for a person's inability to swim, for example, and I'd bet that whoever is in charge of hiring the lifeguards will care more about the latter than the former. It's probably better to be more implicit and point instead to your latest acheivements which will do the talking for you by demonstrating your current preparedness.
