Jim and Frank - in this case, the agreement is with the gender of the speaker, who ' is planning to be more "respectful" of the environment through a change in her habits '.

There are 2 clues here:

firstly, if the agreement was with 'mes habitudes', the adjective would be in the feminine plural as 'respectueuses' - something you can detect in writing but not in speaking obviously, 

and secondly but no less importantly the structure would be ' ... changerai mes habitudes afin qu'elles soient plus respectueuses .. '

Bonjour Frank,

Interesting point  --  I see the adjective in this case modifying the noun "habitudes" rather than relating to the female speaker.

But habitude (nf) would not negate your point so I look forward to the input from others.

Bonne journée

Jim