I was sweating a lot after running to class. / I was sweating a lot after I run to class.

I used to go to work by foot before getting my driving license. / I used to go to work by foot before I got my driving license.

If I drink coffee before going to bed, I can't sleep. / If I drink coffee before I go to bed, I can't sleep.

My body always feels great after exercising. / My body always feels great after I exercise.

I slept all day yesterday after playing games all night. / I slept all day yesterday after I played games all night.

I always feel stressed before having an exam. / I always feel stressed before  I have an exam.

I always brush my teeth after eating breakfast. / I always brush my teeth after I eat my breakfast.

I didn't know how interesting the Louvre museum was before visiting Paris. / I didn't know how interesting the Louvre museum was before I visited Paris.

You should always stretch before-after exercising. / You should always stretch before-after we exercise

I'll go to bed after watching a movie. / I'll go to bed after I'll watch a movie.

I discovered how nice korean are after travelling to Seoul. / I discovered how nice korean are after I travelled to Seoul.

I never drink too much water before sleeping. / I never drink too much water before I sleep.

I didn't know how amazing Hawaii Islands were before visiting the US. / I didn't know how amazing Hawaii Islands were before I visited the US.