if you're not playing as a necessary source of income then you should recognise that poker is something you do for fun with your discretionary free time. So, if it's not fun then don't do it. When you're psyched for it then fire it up. Playing too much or being too focused on aspects (e.g. short term results and bankroll growth) that are out of your control can definitely sap enthusiasm.

Or, a trick. Think of one aspect of poker. e.g. post-flop betsizing. Read about it. Think about it. Play with variations and their implications. Go play a session a stake or two below your normal game and see what happens when you try different things. Read Griffey's blog posts for inspiration.