Meaning trap
work out
exercise
to do physical activity or exercise, especially to get fit or stay healthy.

Don't mix these meanings
Same phrase, different job.
to do physical activity or exercise, especially to get fit or stay healthy.
Another meaning of 'work out' is 'solve or understand'; compare the examples to keep the meanings separate.
Hear it in context
Notice where the phrase sounds natural.
I try to work out at the gym three times a week.
Personally, I believe working out regularly is important for both physical and mental health.
Fix the pattern
One small grammar move makes it sound right.
Not: I make workout three times a week.
Say: I work out three times a week. / I do a workout three times a week.
'Work out' is the verb; 'a workout' is the noun. Don't say 'make workout'.
Which sounds natural?
Tap the one a native speaker would say.
'Work out' is the everyday verb for exercising; 'engage in resistance training' is fitness-manual formal.
Build natural chunks
Words that usually travel with it.
work out + exercise
- at the gym
- every morning
- hard
- regularly
Don't confuse it
Related
Other meanings and phrases to compare.
- work out (solve or understand) — Another meaning of 'work out' is 'solve or understand'; compare the examples to keep the meanings separate.