I used the app myfitnesspal to lose 20 kg. I agree with the music. I used to walk daily for mood improvement one trick is to say that you will go for 5-10 mins and if you are still really struggling after that you can quit for the day but most of the time you can keep on going. I'm struggling at the moment cos I've less fitness and endurance with my pregnancy so the walks are less pleasant and I walk much slower. Plus I'm putting on weight not losing it so I understand how hard it is to keep motivated.
Another thing that really motivated me was seeing improvement in how fast I could walk (or even run!) It happens slowly over time and you have good days and bad days but that was a huge incentive for me to keep on competing against myself to do better.
A saying I really love is "you're doing laps of the people on the couch" so remember that even on your worst days where all you can do is walk 5-10 mins you are still doing better than if you were sitting on the couch (or had stayed in bed!)
Keep it up - you can do it and its great for your mood too