I'm only loosing weight and getting fit for the zombie apocalypse
Are you doing it with help?
I can get fit by myself
It is good to get fit and healthy. Motivating yourself in any way you can is helpful to achieve your goals.
I'm making sure no zombies can get me!
If that is what drives you to get healthier, go for it!  As long as you're aware that zombies don't really exist, because otherwise you may want to talk to a therapist.