I never got the "I'm old and don't feel like having fun" stuff I'd hear from people. but now in my 30s, i can pick up my console controller or log into a launcher and say to myself "you know what? nah".
If I'm going to goof off, i want it to be worth my time when i could otherwise nap or do some chore. So if hearthstone is fun and not a grindy pain in my ass, I'll hop on and fiddle for a bit. i treat it more like an arcade where it's my time rather than a quarter I'm putting in.