As you're finding, there's a bit more to it than just 'motivation'.
I would suggest that only having one meal a day may well be a factor; spreading your food more evenly over the hours is likely to result in a more stable BG levels. Longer periods without food may cause rises in your BG (it certainly does for me) as your liver puts out more glucose to fuel your body when it hasn't eaten and eating only 'supper' at a time of day when you're less active means it is either floating around in your bloodstream or getting stored rather than being used.