Why is it so hard to make exercise a habit? What can you do to make it stick?
Just change the way you think about exercise.
People think that for exercise to work, it has to be unpleasant. Some people can flog themselves to exercise for a few weeks or even a few months out of a sense of obedience, but ultimately they will stop. Eventually, the dislike overpowers the will and they stop.
Yes, exercise can involve some discomfort and certain kinds are more or less effective than others. But all exercise is good for you, any exercise is better than none as long as you are moving your body. If you choose the right form of it, the right form for you, it can be a source of great pleasure.
Everybody’s got different work/life schedules and different rhythms to their daily energy and motivation. Maybe you will love working out at lunchtime or in the evening. You won’t know unless you try different times and different types of exercises. You can find any type of exercise on YouTube.   Make exercise a habit that you enjoy.