The average adult attention span isn’t very long. Depending on where you look you will get varying answers as to how long people can focus for, but generally the average adult attention span is less than half an hour.
People often try to force themselves to focus for long periods of time, but often that is just asking for failure. They quickly get distracted and lose focus.
The same can be said for long-term focus — or rather, your life goals and ambitions. People make New Year’s resolutions all the time. For the first few days their focus is strong. Inevitably though, they eventually lose focus and stop pursuing their resolutions.
One solution to losing focus is to instead work in short bursts of concentrated, focused intervals, and then taking a short break. This is a lot more sustainable than one long period of sustained focus.
The same solution can be applied to long-term goals. Instead of having one big goal or ambition that you are supposed to work towards in a continuous manner, break your goals into smaller chunks, and focus only on those goals.
When you achieve a goal, take a bit of time to celebrate and appreciate your work. Then move on to the next goal.