I have milliion thoughts everyday and they are not about Krishna. Thinking of Krishna can also be a service and valuable use of time. I was listening to Srila Prabhupada once on Mayapur.tv and I don't remember what he said verbatim but it was something like we can keep an impression of deities in our heart. This is just a faint remembrance I don't know what he exactly said.
But I was planning to put pictures of Krishna so t hat i can hold an impression of them in my heart by repeatedly looking at them and thus think of Krishna more.
One devotee was telling me that thinking of Krishna's lilas atleast once a week is very recommended to think of Lord.
Krishna also says I am the taste of water so I can think of Krishna while drinking the water or looking at the beauty of nature Krishna created or who set sun such that it never fails to rise and set everyday.
Any more ways to think of Krishna?