A Stoic and Buddhist overlap.
From Meditations by Marcus Aurelius
The things you think about determine the quality of your mind. Your soul takes on the color of your thoughts (5.16).
It’s not external things that trouble you but your judgement of them—and this you can erase immediately (8.47).
Stick to what’s in front of you—idea, action, utterance (8.22). Concentrate every minute like a Roman—like a man—on doing what’s in front of you with precise and genuine seriousness, tenderly, willingly, with justice. And on freeing yourself from all other distractions (2.5).
The mind is roused and directed by itself. It makes of itself what it chooses (6.8). The mind has no needs except for those it creates. It is undisturbed, except for its own disturbances. It knows no obstructions, except those from within (7.16). The mind without passions is a fortress. No place is more secure. Once we take refuge there we are safe forever (8.48).