The more you do a habit, the more it will become automatic. Forgive yourself for missing a day and thank yourself for the willingness to quickly return to the habit.
By not giving yourself a hard time for missing a day. By continuing the next day. And through continuing this imperfect, uncomfortable route, you’ll be consistent in due time. My meditating was really on and off when I started six or so years ago. I even meditated in bed and fell asleep during many sessions, but that helped me even want to do the practice. Then I struggled with daily practice, but continued on. Now I meditate daily, sometimes multiple times, sitting upright on a meditation cushion. Trust your body to naturally adapt and eventually enjoy and crave your newly built habits. All you have to do is keep taking steps forward.
If I have a day where I mess up I simply start again new in the morning I have had many many days where I’ve gained eight and sometimes 10 pounds in one night and it takes me up to two weeks to get the weight off so I’m happy as long as I haven’t gained 8 pounds overnight again and remember try to remember that the path is zigzags not a straight line but in the end works for the better