In a bodybuilding book the author writes:

Some people dream of the day they reach their ideal body. They begin to
imagine all sorts of doors of opportunity opening up for them.

You’re still going to be the same person, only fitter.
You’re still going to drive the same car, live in the same
house/apartment, and you’ll still have the same problems you had when
your belly was soft.

Getting a six pack can improve your life, but you should never expect
reaching this goal to fix your life.

--- What does the author mean by "fixing" life? Isn't it the same as "improve"?
No. If something is FIXED, that means that the problem(s) that were present have been corrected and it now works exactly as it should. IMPROVE just means MAKE BETTER. FIX is similar to MAKE PERFECT.
I understand. Thank you.