Of course, if we really have no control then we also can't control whether we regret the past or worry about the future, so why bother telling anyone that they

Of course, if we really have no control then we also can't control whether we regret the past or worry about the future, so why bother telling anyone that they should not do it? But of course you had no control over whether you would tell anyone that, so I shouldn't question your decision. The whole notion of 'should' is absurd under such a philosophy.