One at a time.
One day at a time. One run at a time. One mile at a time. One step at a time. Any task can overwhelm even the most talented, competent, and prepared individual if they try to do everything, all at once.
In a long distance race, thinking about every mile while standing at the start line is terrifying. Even more, standing at the edge of the water before a triathlon thinking about the swim, then the hours on the bike, then the many miles of running. Mentally, it is the stress of doing all three disciplines at the same time.
Occupations can be the same way. To become a physician or scientist many stages of training are required. If you want to do medicine and research, the problem is further compounded. Undergraduate education takes 4 years, a PhD or MD take around 4 years (or combined 7-9 years). Then comes at least 3 years of residency, often followed by 1-3 years of fellowship, and for the research minded, a 3-4 year post doctoral fellowship. It’s like graduating from your undergraduate work and realizing you have to repeat kindergarten through 12th grade all over again. Just writing all that down in one place is enough to elevate the stress levels. No one could finish that training by waking up every morning and counting down the days (The count at the end of undergraduate work would be something like 6,200 days left). Planning ahead but also taking each challenge as they come, not mentally all at once, is essential.
The same can be said for other life events. Launching into a responsible adulthood does not mean buying a car, getting a mortgage on a house, finding your life companion, starting a retirement account, and getting a salaried job all at once. It means gradually progressing towards the long term goal of independence.
So whether in a race, an occupation, or life in general, it is important to take the next step without fighting every battle and taking on every future challenge all at once.
“Do not worry about tomorrow, for tomorrow will worry about itself. Each day has enough trouble of its own.” (Matthew 6:34)
This however, is often easier said than done.