How do you write a weekly journal on exercise?

it depends on what you are writing it for. if you are writing it for a blog or something similar then you may have to follow a specific format. but if you are writing if for personal reasons you can write it in any format that you want. including and excluding details that you want.

but it may be a good idea to include

• day you entered it
• workouts done that week
• any new goals achieved.
• future goals
• personal plans for the future