Pushover

someone who is easy to "push around" (make him/her do what you want) すぐ影響を受ける人；頼まれやすい人

Examples:

1.

A: The manager asked me to work late again tonight!

B: And you said "yes"? Geez, you're really a pushover, aren't you?

2.

People are always asking me to do favors because I'm such a pushover.

3.

Wow, I thought you'd be a pushover, but I see I was wrong. You're pretty tough.

4.

Let him see I'm no longer the pushover I was last night!

5.

In the early part of this century the mountain had a fearsome reputation, and Ewen MacAskill found it to be no pushover.