Wear a mask, or a face shield, in some situations both, wash your hands, practice social distancing, six feet, more when you can, moderate exercise, enough sleep, avoid touching your face, and follow the other recommended practices to stop the spread and keep yourself safe.
If you want to live and avoid any long term health effects wear a mask.
To protect your friends and family wear a mask.
To serve society and humanity wear a mask.
To drive COVID-19 into extinction wear a mask.
To bring back the economy and get people back to work wear a mask. As long as COVID-19 is killing lots of people the affluent will be reluctant to spend their money on personal services and the economy will decline and unemployment will be high. The government can allow businesses to open but that is not enough. There is no substitute for bringing COVID-19 down. There is no trade off, wear a mask.
To reelect Trump, if you want to reelect Trump, wear a mask. In Europe Germany has done well and Angela Merkel popularity has soared. The United Kingdom has done terrible and Boris Johnson's popularity has plummeted. There is no substitute for success. Trump needs rapid progress on COVID-19. Wear a mask.
To give doctors and scientists time to development better treatments and hopefully a safe and effective vaccine wear a mask.
To give business time to increase production of masks, face shields, and other personal protective equipment, ventilators, COVID-19 tests, and other supplies and equipment to deal with COVID-19 wear a mask.
To give governments time to increase testing and contact tracing wear a mask.
To give governments, schools, businesses, and churchs time to figure out how to open safely wear a mask.
To give science time to determine which activities are safe and which are dangerous wear a mask.
Obviously wear a mask is just short for following many different safety techniques.
The more you can follow the better. The objective is to get the r below one. If on average an infected person infects less than one person COVID-19 will become less common and move toward extinction. If the r is far below one, if a hundred infected people only infect fifty, then COVID-19 will move quickly toward extinction. So wear a mask.