“Yo tengo un ego muy grande” (I have a big ego)
In English it sounds perfectly natural to say: “I wake up at 8:00 am. I eat breakfast at home, and then I drive 30 minutes. I arrive in my office at 9:00am.” Literally translated in Spanish would be: “Yo me levanto a las ocho. Yo desayuno en casa y luego yo manejo treinta minutos. Yo llego al trabajo a las nueve.”
If you say it this way in Spanish, your friends may cringe and make fun of you and say something in reference to what a big ego you seem to have. You see, expressing yourself in this literal translation, it comes across more as if you are a self-centered person who thinks only of himself than of actually simply describing your morning routine. The reason is that we Spanish speakers very rarely use subject pronouns in front of verbs (yo, tú, él, ella, etc.). They are not necessary since the ending of the conjugated verb already indicates the person who is completing the action, (i.e.: hablo can only mean “yo”, hablas can only mean “tú”, etc.). A similar problem arises when you refer to others constantly by “ella, ella, ella”, or “nosotros, nosotros, nosotros”.
The correct way to express the above example would simply be: “me levanto a las ocho, desayuno en casa y luego manejo treinta minutos. Llego a mi oficina a las nueve.”. You could start with one “yo”, as in “yo me levanto”, but you would be wise to say it no more than that.
With that said, there are exceptions, of course. If you need to emphasize, sometimes the use of the subject pronoun is helpful: “yo no cocino mal; yo soy un buen chef.”. This also helps to distinguish parallel structures: “yo voy a Boston y tú a California”.