Only what happens now happens later
Sometimes tomorrow means tomorrow, but most of the time it means never.
Sometimes I hope that I'll be fully present at a later time when something important is coming up. I want to make that sure I'll be present when I go on a hike with my friend later that day. But this won't help me actually be present in that moment, and is also taking me out of this one. The best way to be present then is to be present now. **The best way to make change then is to make change now. **
I similarly sometimes find myself perpetually excited for the future. I can't wait to go on vacation, but when I'm on the vacation, I can't wait to come home, and when I'm home, I can't wait for... Instead of being present and joyful like I imagined myself in each future time, I repeat the same pattern: wishing to be in some imagined and better future moment.
The next time you consider whether this is the day you start eating healthier, it'll be easy to make an excuse to start tomorrow. If you choose tomorrow, tomorrow will come, and it will again be today. You again have all the excuses from earlier and now more momentum and fear leading you to choose tomorrow again, because you already chose it once. Postponing action becomes a habit. This is how tomorrow becomes never.
The only way you'll make it easier and more likely that you eat healthier tomorrow is by eating healthier today. In this way you build up momentum that's in your favor and adjust both your habits and identity to be closer to the self you want to become. Identity change is necessary for long-term behavior change.
TLDR:
Stop imagining that there will be some perfect time in the future for you to start making change. That time is now. You'll always have great excuses to avoid action.
References:
"It is only by being fully in this moment that any future moment might be one of greater understanding, clarity, and kindness."
"Only what happens now happens later"
"Every action is a vote for the type of person you want to become"
Unknown
"The best time to plant a tree was 20 years ago. The second best time is now."