Some days I cannot be bothered to go to the gym, especially after a long day at work. If I'm in this mind set I don't set unrealistic targets and I'll pick a slow activity like Yoga or swimming.
I have set days that I train and I do my upmost to keep to them, but things change and I'll have to work around it. I don’t beat myself up if I can’t make the gym though, as I find it doesn't help, I'll just set a goal for the next training day and focus on that.
I also find it really helps to prepare my meals a couple of days in advance, mostly my lunches, and I have two fridges at home for all the fresh fruit and veg we eat.
I always make sure I eat breakfast but if I have to go to work extra early, I take it with me, as I find I can't eat too early.