That next hill is always harder than the last one.
Even if it is the same size, you’re already tired from the one you just finished climbing so it looks bigger, badder, like it’s going to hurt even more if you try.
Or perhaps it is bigger, substantially bigger than what you are used to and/or have experience in the past.
Whichever it is, there is a Hill and it is blocking your path, it could be made up of physical things – code, writing, work, whatever – or the less tangible, harder to measure – goals, people, success.
Whatever it is, it’s a Hill, it’s in front of you and it’s not going anywhere.