How do I remind myself to run in-flight checklists?
In my view, the best tool for reminding yourself of recurring "household chores" is by using a timer, if the noise profile of your aircraft allows it. (Try it! You can probably hear more than you think, even in a loud prop). Either use a kitchen timer (which has a really simple physical interface, although two hands may be required) or your smartphone (a bit more complex interface, typically allows for single hand usage, with the added benefit that you can run multiple independent timers, and that the alarm will not stop sounding until you dismiss it). Modern GA EFIS (for example G1000) typically have timing facilities built in.

If you are unable to use an actual timer, determine the interval of the task (for example every 15 minutes), and use your normal watch. (For example "Check the tank every time the minute-hand passes the 0, 15, 30, 45 marks").