If what you want to say is Live! (= Don´t waste your life! Seize the Day! Live your life intensively!, etc.), the Spanish imperative is ¡Vive!. English "alive" is an adjective, as in "They are alive!" (from "They are on life"). The Spanish equivalent is the adjective "vivo/a(s)", but you cannot construct it in the imperative, so what you want is Spanish "¡Vive!"

vivo/viva.. for example: Im alive - estoy vivo/viva

Para mujer: "Estoy viva". General: "Viva la vida"(celebrate) "Vivir"(more general) "Vivir la vida"(enjoy and pleasure) I recommend you: "Inmersa en el presente" that sound good. Or "Inmersa en el aquí y ahora". That have a little little hedonist tendence: "Vivir la vida" or "Inmersa en el presente". That is too inocent to me: "Viva la vida". But sounds good. That really like, my opinion: "Inmersa en el aquí y ahora"...that have a little spiritual tendence and you too use in "hedonist" sense...or inclusive inocent. ;)

The imperative could be "Vive" (informal) or "Viva" (formal). Another informal opcion is "Viví"... That form is more common used in Argentina but not too much in Spain =)

If you're talking about something feminin, you must say "VIVA". Otherwise, you have to say "VIVO". If you want to say "I'm alive!", say "¡Estoy viva!" cause you're a woman. If you need to say "I live", just say "Vivo" (no matther if you are a boy or a girl because it is only the verb.)... Anyway, I think you should not use only "vivo" because it sounds a bit strange ...