You haven't chosen to resit your GCSE in maths, but to get to where you want to be you almost certainly need it.
Next time you're struggling with your equations, or trying to make sense of a problem, remember that GCSE maths is a means to an end. Some skills are vital for your future, in a job that may not have been invented yet, but some are needed only to open the door that may be closed to you without a 4.
"Get the 4 and open that door!"
Maths is a skill, like the long jump or playing the trumpet. Some people are irritatingly, naturally good at it. The rest of us will just have to work hard.
Human beings are selfish and lazy. If we like something, we'll invest time and effort into it, if we don't we'll avoid it. Motivating yourself to work on something you don't enjoy is hard. Right now you're having to do your GCSE maths again, next week it may be cleaning your bedroom, next year it could be writing a report for your boss. We all have to do things we don't enjoy as part of our everyday life. Being successful is about pushing through the dislike and applying the effort necessary to fulfil the vision.
"Dreams don't work unless you do."
It is important to put your effort in the right places and work in the right way.
A task will take as long as you allow it to. How and where you work is just as important as what you are working on. Avoiding distractions, taking and scheduling the right amount of break time and knowing what you want to achieve are all key here. Establishing a good working pattern will make you more successful and knowing what work you intend to do before you start working is vital. Plan what maths you are going to do and when you are going to do it. Work in small chunks but regularly, little and often is usually best.
"Work smarter, not harder!"
There is no substitute for practice, especially in maths. Maths is probably the complete opposite of riding a bike. If you don't use it, you will lose it!
Getting good at maths takes hours of practice, and a lot of that practice is not fun! Much of that practice also feels irrelevant but is actually vital. Why would a long jumper need to visit the gym to lift weights? Why does the trumpet player need to practice scales? Much of maths is like this, for example: the times tables. Knowing your times tables is vital in almost all areas of GCSE maths and to be successful regular recall of them is needed to keep you "fit" to tackle the problems you'll face.
"Practice makes better!"
There is no true victory if defeat was never an option or an experience.
It is definitely true that you learn more from your mistakes than your successes. Failure tends to play on your mind much more than success and how you respond to this will define you. If you only attempt things you can already do then you will never grow so don't be afraid to fail, be afraid of not caring enough to try.
"The hardest part of the game isn't even playing the game. It's caring enough to care about playin' the game"