How to politely refuse a friend's invitation?

In daily life, interpersonal communication is inevitable. When a friend invites you, you don't want to go or have something to do, we have the right to refuse. Some people are embarrassed and don't know how to refuse others, for fear of hurting their feelings. So how can they politely refuse other people's invitations without offending others?

As a way to refuse an invitation, the most basic thing is to give reasons for not attending the invitation. But it's hard to say "I'm not interested". After all, we are all adults, and it really hurts to refuse people naked.

Lying at this time is also a stopgap measure, so it would be better to quote the reason that "there is a company meeting that can't be pushed off" and "my relatives are in hospital and I have agreed to visit" here, so that friends can frankly say "there is really no way".