There could be a biological reason why you are bad at planning!

Learning how to plan - especially if you're new to organizing your time - can be a frustrating experience. And for some individuals, the reason could be their brains. Those with natural brain dominance in the back-left part of the brain are most comfortable making linear plans and following them. These individuals often don't understand why others struggle. But those with brain dominance in a different quadrant of their brain will find planning much harder. That's because the neurochemistry of their brain causes them to use 100 times the energy to think in "planning" mode as someone whose natural dominance is back left. More here.