READ OUT LOUD. Choose which marked text you prefer to practice with - macrons in verse form, or macrons in prose order, or accent marks in prose order, or focusing on the meter. You will find materials for all of these options below. :-)
VERSE MACRONS. Here is the verse text with macrons:
Strātus humī fuerat Taurus; Mūs forte momordit

Hic nusquam cernī potuit: bōs cornua frustrā

"Parvula nē spernās; tē Mūs impūne lacessō,

PROSE MACRONS. Here is the same text with macrons written out in prose word order:
Taurus humī strātus fuerat; forte, Mūs crūra momordit. Ille, hostem petēns, cornibus ruit; hic nusquam cernī potuit. Frustrā, bōs cornua vībrat; dēnsa tamen herba tegit quem petit. Mūs inquit: "Nē parvula spernās. Impūne Mūs tē lacessō! Ā minimō maximus laesus erās."
STRESS (ACCENT) MARKS. Here is the prose text with accents, plus some color-coding for the words of three or more syllables (blue: penultimate stress; red: antepenultimate stress):
Taurus humi stratus fúerat; forte, Mus crura momórdit. Ille, hostem petens, córnibus ruit; hic nusquam cerni pótuit. Frustra, bos córnua vibrat; densa tamen herba tegit quem petit. Mus inquit: "Ne párvula spernas. Impúne Mus te lacésso! A mínimo máximus laesus eras."
ELEGIAC COUPLET METER. Below I have used an interpunct dot to indicate the metrical elements in each line, and a double line || to indicate the hemistichs of the pentameter line.
Strātus hu·mī fue·rat Tau·rus; Mūs· forte mo·mordit

Hic nus·quam cer·nī potu·it: bōs· cornua· frustrā

Parvula· nē sper·nās; tē· Mūs im·pūne la·cessō,

IMAGE. Here's an illustration for the fable (image source) from a 15th-century edition of Aesop's fables:

What follows is an unmarked version of the prose rendering to faciliate word searches:
Taurus humi stratus fuerat; forte, Mus crura momordit. Ille, hostem petens, cornibus ruit; hic nusquam cerni potuit. Frustra, bos cornua vibrat; densa tamen herba tegit quem petit. Mus inquit: "Ne parvula spernas. Impune Mus te lacesso! A minimo maximus laesus eras."