You're going to leave, but you're coming back tomorrow. What would you say?
a. Ven conmigo mañana.
b. Me siento muy bien.
c. Pues todo anda bien.
d. Mañana volveré.
You would choose answer d). Mañana means tomorrow, and volveré is the verb 'volver' (come back) in the future sense, conjugated in the 1st person, singular. This sentence literally means 'Tomorrow I will come back'.