Being thoughtful simply means thinking of others before yourself. What you say or do will have an effect on
others. So it is important that you think before you say or do anything. In this way, you can avoid hurting
others' feelings. Moreover, a thoughtless act or remark can spoil a perfect relationship.

Children should be considerate of old people. 体谅
mean to do 打算做 mean doing 意味着
When I say I mean to do it, I mean it.
essential = necessary / important
It is important that he (should) be punctual.
a piece of cake
It is cinch(俚easy).
feeling 感觉 feelings 感情
scold 责骂
undermine 破坏(少用)
bear 牢记 = remenber
likewise 同样地
Yesterday was a lousy day. By the same token today does't look any better.
What goes around comes around.