Lekarz mówi, że zdrowy spacer pomaga łatwiej odzyskać energię.

In Polish, że is a conjunction used to introduce a subordinate (dependent) clause. Whenever you report what someone says or think, you link the main clause to the subordinate clause with że. Standard punctuation calls for a comma before że.
Example structure:
– Main clause (Lekarz mówi),
– comma,
– że + subordinate clause (zdrowy spacer pomaga łatwiej odzyskać energię).

Zdrowy spacer is the subject of the verb pomaga. In Polish, the subject of a verb typically appears in the nominative case. Here:
– zdrowy = nominative masculine singular adjective (“healthy”)
– spacer = nominative masculine singular noun (“a walk”)

The verb pomaga (“helps”) can be followed directly by an infinitive to mean “helps to do something.” For example:
– Pomaga mi nauczyć się (It helps me learn).
In your sentence, pomaga + odzyskać energię means “…helps (to) recover energy.” We use the perfective infinitive odzyskać because we’re talking about the single action of regaining energy, not an ongoing or repeated process.

Łatwiej is the comparative adverb of łatwo (which means “easily”). In English you’d say “more easily” or “easier” in this context. Comparatives in Polish often end with -iej for adverbs:
– łatwo → łatwiej (“more easily”)

This sentence states a general truth: “A healthy walk helps recover energy more easily.” No specific person is indicated, so no dative pronoun (mi, ci, etc.) is needed. If you wanted to say “helps me,” you’d include mi:
Lekarz mówi, że zdrowy spacer pomaga mi łatwiej odzyskać energię.

Yes. A more formal or “noun‐based” version uses pomaga w + noun in the locative:
– Lekarz mówi, że zdrowy spacer pomaga w łatwiejszym odzyskaniu energii.
Here w (“in”) requires the locative case, and odzyskaniu is the locative of odzyskanie (a noun, “recovery”).

Że introduces reported speech or a fact: “Doctor says that…”
Żeby introduces purpose or intention: “in order to…”
If you wrote Lekarz mówi, żeby zdrowy spacer pomagał…, it would sound like the doctor is ordering someone: “Doctor says so that a healthy walk would help…,” which is not correct here. Use że for “that” in reported statements.