If you fall off your horse, get right back on again. If you fail in your habits, do not let this spiral out of control, just get back into them as soon as possible. Avoid the thinking that goes like, 'well I have had a cake today, so I may as well eat crap for the rest of the day.' This leeches into 'well I was bad on Monday and Tuesday, so I may as well write this week off,' to 'well I was bad last week so I may as well just wait until next month to start again.'
Why are you trusting your future self to be better, to have fewer cravings, to have more motivation than your current self? Because you have felt motivated in the past, you think it will return? Possibly, but why take the risk? Why leave it up to fate? If you just did the thing you know you should do, the action itself will produce motivation, not the other way around.
There is no future, only what you are doing in the present. Right now.
The future is just a series of presents that stretch out in your mind. You do not delay breathing in such a manner. 'I can't be bothered to breathe right now, I think I'll wait until tomorrow.'
Bring your thoughts to your breath. Gather yourself in the present moment and then take action now. Get yourself back on track. Eat healthily, be silly with a loved one, open that stocks and shares account.
What would it look like if it was easy? Do that.