When things are going smoothly, you might be lulled into believing that you don't need to meditate regularly and that you're "too busy". But that would be a mistake. Working on our minds takes consistent practice. It's much harder to sit down and meditate when you really feel like you need it.
When you get to a point where you're stressed and feel you "need" a sense of balance and calm, it'll be too late to start or restart meditating and reap the benefits immediately. There's no switch you can turn on and off. That means that often, the most important time to build a meditation habit is when you feel like you don't need to.
And remember, meditation doesn't have to mean the act of sitting still and doing nothing. If you can keep yourself immersed in the present moment and catch yourself when your mind is wandering off, as you go through your daily routine, you haven't actually "missed" a day of practice.