How to express my feelings of neglect to my boyfriend...?

Well My boyfriend for the past year has steadily become busier and busier. Long story short at the present moment he is leaving for boot camp in 2 weeks. He works out practically every day of the week at a martial arts place for fun i guess and to get in shape...I used to see him once a week but this past week he came over two days for around 5 hours before having to leave for workouts or work at home...I know he isn't cheating because he still has strong emotional attachment to me when we see eachother its like when we first started dating...however I feel that he is taking his workouts too serious but he is determined to do well at that and the army...any who, He is leaving for a youth gathering trip tomorrow and i dont know how long he will be gone. I feel a little neglected by this because I dont really understand how this youth gathering can be more important than spending his remaining time with me. I just need a way to express my feelings without blaming him and bringing him down...I just dont understand why he can take a whole day or maybe few days off of working out to go to a fun youth event, but he can't take a full day, just one day, off to see me...