If it were quick and easy, they would have come.
Excuses sworn by Allah
Ibn Kathir says this addressed the hypocrites who stayed behind from Tabuk. Had it been nearby gain and a short journey, they would have come. But the road to Syria was long. On his return they would swear: if we could, we would have gone. Allah knew they were lying.
The charity event is two hours away, so you suddenly have a headache. The study circle is on a rainy night, so you are "swamped." Be honest with yourself about the difference between cannot and will not.
I would have helped, I just could not this time.
Many of my can'ts are won'ts. Allah knows which is which.
The next time you give an excuse, ask yourself honestly if it would stand if the task were easy.