With three you don't get tired
With four if you play with me, you can get fired
With six I have an arachnid anagram
With all my seven you need to get into a health program
Inspired by @tyobrien's template
With three you don't get tired
With four if you play with me, you can get fired
With six I have an arachnid anagram
With all my seven you need to get into a health program
Inspired by @tyobrien's template
Just a guess, some are a stretch...
Cardiac
With three you don't get tired
Car - If you have a car, you can drive everywhere and not walk.
With four if you play with me, you can get fired
Card - If you play with the company expense card and put too many charges on it, you could get fired
With six I have an arachnid anagram
Cardia -> Acarid - 6 letter anagram of a subclass of arachnid
With all my seven you need to get into a health program
Cardiac - If you have heart problems, you'll need a health program