He listened to what Pop said, worked his ass off and earned a spot on this team. Seems praise-worthy to me. If you ask Fin why he didn't do this years ago, he'll probably tell you that's an excellent question.
As you get older the same things that worked in the past don't work anymore. When you are 25 you can eat whatever you want but then around 30 your body starts storing it, gradually a little more all the time, so you have to adapt, and it can easily catch you by surprise. It's easy to convince yourself that it's not happening to you or to just not realize it's happening because it's so gradual. Like I mentioned earlier, with the extra weight sometimes comes extra pain, and that contributes to the beating your body takes playing an NBA schedule. Finley shoots for two hours before almost every game, so there's not much sense in questioning his work ethic.
There haven't been many harsher critics of Fin around here than me, but if he's contributing now then that's all that matters. The combination of improving his quickness and strength and reducing his pain might even mean he starts playing defense again. He used to be a really good defender.