0 towards the direction behind you -- 後ろへ, 後方に
2 with the part that is usually at the front at the back -- 前後逆に
3 in one direction then the opposite way, many times -- 行ったり来たり, 前後に
4 to try extremely hard to help or to please someone -- 全力を尽くす, 一生懸命に努力する
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.
道路がどれだけ長くても、一歩一歩完了することができますし、足跡をマークしなければ、道路がどんなに短くても完了することはできません。