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To add to Guyomar's excellent (as usual) answer:

By itself, cansar does not mean to “get tired”; it means to “make tired”. Eso me cansa — that makes me tired. (Tú) te cansas — literally, you make yourself tired, or in idiomatic English, you get tired. We cannot omit te without changing the meaning. We can (and usually do) omit tú, except for emphasis (or in some Caribbean accents). Another example: bañar - to bathe (someone else). Belquis bañó a su hijo — Belquis bathed her son. Belquis se bañó — Belquis bathed herself (or, in idiomatic English, Belquis took a bath).

This is a very important grammar point. I’d recommend you go to your textbook (or search terms "ELE verbos reflexivos / verbos pronominales), study the relevant chapter, do all the exercises *out loud*, slowly, and accurately. Then, you should practice using reflexive verbs to make your own sentences — again, out loud, slowly and accurately.

The pronominal verbs described above are reflexive (oneself). There are also reciprocal ones (“each other”) and ones that are more idiomatic — see the link below for the idiomatic ones.

My attempt at sharing what I've learned is seen as marketing. So sorry to have bothered anyone.