<human>: Throwaway for obvious reasons.

I've been at my job for a little over a year. The company is a really great place to work, and they've treated me very well, but I decided that I really want to earn my PhD, so that's what I'm leaving to do (I will be spending the next year on research to boost my application, and applying next summer).

I'm feeling really worried about giving my notice, because the job I'm at has a particularly long training period, and when I applied for the job I really thought I could grow with the company, so I negotiated for a salary, etc. 

I know I have to woman up and just do it one way or the other, but I'm feeling so ungrateful and awkward about the whole situation. I have a lunchtime meeting with my boss in a few hours (I'm in the US) and I need to tell him then. Any advice or words of encouragement would be appreciated!

Can you summarize the given text in a few sentences?
<bot>: leaving job to go pursue academia; been there such a short time I feel ungrateful leaving. How do I get through this?