Choosing to better yourself is not an easy decision. When you have become acclimatized to the same old habits you have always had, moving past them can be an uphill struggle. It's all the more reason to congratulate someone when they leave that toxic relationship, land that dream job, or start exercising regularly for the first time. It takes effort.
This was part of the reason that one anonymous man received the widespread ire of the internet after he decided to criticize a woman that he didn't know for jumping rope in her driveway. She seemed to have her confidence knocked by the unsolicited remark, but most people couldn't wait to question what this dude's problem was. Exercising can be something that makes many self-conscious, despite the fact that it is good for us. It isn't in anybody's best interests to tell someone that it is something that nobody wants to see.