Using the infinitive (not the gerund) as the subject/object of the verb

In Spanish, when "activities" are the subject or the object of a sentence, we use the infinitive form. Note that in English the equivalent sentences tend to use the gerund (-ing ending) instead.

Have a look at some examples:

If you ask the question ¿quién? (who?) or ¿qué? (what?) about the verb it will give you the subject or the object of the verb. In these cases, to know about the subject you always ask ¿qué? (what?) because we are talking about "activities".

For example:

• What is bad for your health? Smoking (the subject of "es") = "Fumar".
• What is advisable for everyone? Having a balanced diet (the subject of "es") = "Tener una dieta equilibrada."
• What do doctors recommend? Drinking (the object of "recomiendan") = "beber mucha agua".

Look at how infinitives act as objects when using some modal verbs, like "preferir" and "necesitar". For example:

A typical case that uses the infinitive for any activity expressed after the verb is gustar and verbs that work like gustar.

Remember that the activity is always the subject of the sentence with these types of verbs, i.e "Doing something pleases/interests/bothers... someone".

Here are some examples:

Using the infinitive with impersonal statements, e.g. "Es bueno...", "Es importante..."  is also very common. Here, the subject of sentence is the infinitive, for example: