Yes, but then laziness is not a highly valued human quality, so next time whenever you need help, people might feel about it the same way. And if someone gives

Yes, but then laziness is not a highly valued human quality, so next time whenever you need help, people might feel about it the same way. And if someone gives that reason on a habitual basis, it might just actually mean he is not a helpful person. However, if you give them a short genuine reason of why you can't do it at that time, may be you'll have some hope.