I don't understand what underlies me...

While saying it's for people, people say thank you if you do this. Don't you have a plan in your head that you don't want to be used or something like that?

Those thoughts make me suffer. If you can't take it for granted like yourself, I think you should stop doing it willingly. Learn for yourself. It's important to know how you are.
It would be nice if you could learn Buddhism and have a sense of compassion that you can take for others as a matter of course.

In a world where people take their eyes off the living horse, I think it's precious to “take the initiative and be kind,” but at the same time, I definitely think there are times when people who are “convenient” = easy to use. It's lonely.
However, “not for others” may be a “makeshift” of getting answers now for the time being in response to the “feeling of asking for something in return.”
When you say that, you may feel completely dark, but from my point of view, it actually looks like the timing of using “not for others” is wrong. I mean.
I think it's a matter of timing when you do it, not “because it wasn't for others,” and when something came back, you realized, “Oh, it wasn't just good for others.”
I think you've probably already established the idea of “helping others in need” in your body. So if you “suddenly” want to try your hand at it, that's fine.
What I don't understand is that “kind people” usually become more dependable, so it's hard to think they'll have fewer friends. If there is a mechanism, what are the benefits you have gained by “not refusing, agreeing, and making things convenient.” (Normally, we don't pay much attention to the side effects of the benefits)
Sometimes parents say, “I want to make whatever my child says come true.” But this is a path of failure. Not everything is right for children, and it is the role of parents to show limits and barriers that sometimes say “nothing more than this is good.” Parents who say “anything” have passed “efforts to reconcile and come to terms with the child's intentions and parents' thoughts, and clean up after what they have denied.” Then the children escalate, and both sides who are not used to coming to terms become “sharp and disconnected.” Is it possible to follow that kind of path when you say “I've lost my friends”? I think so.
In any case, you can keep updating your “beliefs about living” more and more. When upgrading a version, it basically includes “doubting what you took for granted.” I think the fact that you are facing problems now is proof that your time to grow is near.
When it's not “suddenly,” I think negotiations, or rather satisfaction, are necessary.

One teacher asked, “What's the difference between a Bodhisattva and a Buddha?” When I heard that,
“Bodhisattvas think people must be saved. The Buddha can save people without having to save them. That's the difference.” I received the answer.
You are precious as a Bodhisattva act, but you are bound by the fact that you have to save people and be kind to others.
There are also various types of volunteering mentality.
When it comes to compulsory, intrusive volunteering where you have to do it, and you absolutely have to do it, it's very difficult for the people to volunteer.
If you're bound by your own rules you've made yourself, and that makes you unhappy, then those rules are the ones you should throw away.
But it's hard for you to throw it away. I have the illusion that it leads to self-denial.
There is no such thing. If you just throw away that rule, you'll be instantly renewed.