Hm. Well, first, I want to wish you the best of luck. Focusing on you is a great idea if your BF is going to be gone, it will also help you to stay busy and not miss him so much.
I can only offer my perspective from my most recent program. I was doing (and still am) an exercise program called P90x which is daily exercise about 1 hour long, different stuff every day. It's HARD. To stay motivated, I joined accountability groups online, I watched success videos every day, I read success stories, I bought some cute workout clothes that I'd want to wear (and would only allow myself to wear if I did the workouts, haha), I wrote down my progress every day, I tracked my weight, I saw my doctor regularly for checkups...I mean, literally, I LIVED this program. I told people I was doing it, so that they would ask me and help keep me accountable. My DH would ask me, when he came home, if I'd done my workout yet. Every little thing helped. I'd remember sometimes WHY I wanted to do this. What my goals were. I needed to lose weight, of course, but also I needed to drop my cholesterol (which I succeeded in doing- 80 points down in 3 months!) and I needed to get in better physical condition for my outdoor activities that I love to do. It really helped when people who hadn't seen me in a while saw me and were like, WOW! Because it made me feel good that they noticed. Even my boss, who sees me every day, noticed pretty quick.
I literally LIVED my program. Keeping my diet clean was something I focused on at every meal, and doing my workout each day was what my schedule revolved around. It sort of was like what Earl Nightingale says in "The Strangest Secret"
that you become what you think about. Well, I was thinking about my diet and my exercise program a lot throughout every day. I was thinking about my goals every day. And because of that I did finish the 90 day program, took 2 weeks to do some other types of exercise, and now I've re-started the program for a second round.
That is what worked for me. I hope you find a method that works for you!