(inspired by today's comic...)
Look at a 16-to-26-week training plan for a marathon, or a half-marathon.
Count the miles, or minutes. Better yet, consider both measures; duration AND distance.
It's daunting to look at a plan in terms of distance, minutes (hours!) and workouts. Especially when you compare training time to the (relative!) brevity of the race distance and duration.
If we try to take the entire thing in at one fell swoop the odds are great we'd "choke" mentally, emotionally, socially, maritally, and maybe...physically!
Now, cover up all but a single week. Even a "long run" week seems more achievable.
Get a little more granular and look at a single day. Training for one day is simple - which might not necessarily mean the same thing as "easy."
But that's all you can deal with; all you should deal with at a time. One day.
(It's the reason I don't provide much granularity announcing my workouts. I don't want to scare anyone off with a workout that appears too difficult. I don't want to tie myself to a particular distance, modality or intensity only to find an athlete is feeling poorly, or the weather conditions suddenly change, or - like recently - the track is being repaired. That kind of stuff.)
Becoming a good or a great runner, becoming a lifetime runner, all boils down to doing what can be done in the space of one day...and replicating it as often as our minds, emotion, life, family and body will bear. We can use those days which won't allow us to replicate to rest, recover, repair and reload.
It's the answer to the riddle: "How do you eat an elephant?"