costar (trabajo/tiempo/esfuerzo): suponer o requerer cierta cantidad de recurso o dificultad. [Uso: 'costar tiempo' se dice más en España; a menudo se omite el objeto directo de 'costar'].
-No quieren perder lo que tanto esfuerzo les costó conseguir — They don't want to lose what they worked so hard to achieve
-Me costó trabajo convencerlo, pero acabó por aceptar — I had a hard job convincing/struggled to convince him, but in the end he accepted
-Terminar esto nos va a costar tres días — It's going to take us three days to finish this
-No cuesta nada ser amable — It doesn't hurt/It's not hard to be pleasant
-¿Te ha costado encontrar aparacamiento? — Did you have trouble finding a parking space?
-Me cuesta la vida expresar mis sentimientos — I find it excruciatingly difficult to express my feelings [≈Muchísimo]
-Me cuesta un mundo levantarme en invierno — For me, getting out of bed in winter requires a herculean effort [≈Muchísimo]