Learn Spanish (Latin America): Mi rutina es meditar a menudo.

A menudo means "often". Unlike single-word frequency adverbs like siempre (always) or nunca (never) that usually go right before the verb, phrases like a menudo are more flexible. They very commonly go after the verb or at the very end of the sentence, just like in English: "to meditate often" (meditar a menudo).

Why do we use the infinitive meditar here instead of an "-ing" word like meditando?

In Spanish, when you want to use a verb as a concept or a noun—like saying "meditating" is your routine—you always use the infinitive (the basic form ending in -ar, -er, or -ir). So, Mi rutina es meditar translates to both "My routine is to meditate" and "My routine is meditating".

Does a menudo ever change to a menuda because rutina is feminine?

No. A menudo is an adverb phrase, and adverbs never change their gender or number. Even though rutina is a feminine noun, a menudo stays exactly the same.

Why use es instead of está when talking about a routine?