He is lobbying to influence politicians.

He is known as an activist for environmental issues.

He is a very active person.

Action potential is an important mechanism for nerve cells to transmit information.

He is actively participating in social movements.

He is passionately engaged in extracurricular activities.

The United Nations Environment Programme is providing solutions to global environmental problems.

He likes to take a walk in the park at dusk.

He engaged in an extravehicular activity from the spaceship.

He is undergoing training for extravehicular activity.