- Why are you playing your current character?
- How does your current game let that happen?
Basically, if you're playing a character odds are there is a reason. And if the character is in a game, the game should be doing something to help that thing happen.
If you can't answer the first question, than you may have no purpose in playing the character which can make for a flat character or one that will peter out and be unfun at some point in the future. If you can't answer the second question, then the game may not be enabling what you want out of the character, which can lead to unfun sessions or a game you don't care about as much.
In both cases, not being able to answer the question merits a conversation with the GM about the character, the game, and how you can make those things happen. However, keep in mind that you're not always going to have deep answers to the questions. Sometimes the answer to number one is "I'm playing my character because I like Rogues" and "The game lets that happen by letting me be a rogue and do rogue-ey things."
Perhaps the answer is deeper for some?
In my friend's Star Wars game I'm playing a cowardly mechanic. I'm playing the character to explore being a support character from a different angle I normally do. It is also letting me have fun with a character with super low willpower that constantly makes bad decisions they have to weasel out of. The game lets me do this by giving me opportunities to make horrible decisions and try to weasel out of the consequences, both against NPCs and PCs.
What about you?