exercise.

Any activity designed to develop or hone a skill or ability.

The teacher told us that the next exercise is to write an essay.

Activity intended to improve physical, or sometimes mental, strength and fitness.

I like to do my exercises every morning before breakfast. I do calisthenics for physical exercise, and I do crosswords for mental exercise.

Activity intended to improve physical, or sometimes mental, strength and fitness. Such activity of physical nature, for physical fitness (plus also mental benefit).

Swimming is good exercise.

She does stomach exercises every day.

Activity intended to improve physical, or sometimes mental, strength and fitness. Such activity of mental nature, for neurocognitive health.

Such exercises as puzzles and chess can help keep the mind sharp as we age.

A setting in action or practicing; employment in the proper mode of activity; exertion; application; use.

The law guarantees us the free exercise of our rights.

We urge the exercise of patience and restraint.

The performance of an office, ceremony, or duty.

I assisted the ailing vicar in the exercise of his parish duties.

That which gives practice; a trial; a test.

To exert for the sake of training or improvement; to practice in order to develop.

to exercise troops or horses;  to exercise one's brain with a puzzle

To perform physical activity for health or training.

I exercise at the gym every day.

To use (a right, an option, etc.); to put into practice.

exercise caution

The tenant exercised his option to renew the tenancy.

To occupy the attention and effort of; to task; to tax, especially in a painful or vexatious manner; harass; to vex; to worry or make anxious.

exercised with pain

It is not a question that has exercised me greatly in the past.

To set in action; to cause to act, move, or make exertion; to give employment to.