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:
Dūrārī lapidēs indignē Cēra ferēbat,

In flammās ideō sēsē abiicit illa camīnī,

Haec cecidēre tamen secus, igne solūta liquescit,

Affectāre cavē rem, quam nātūra negāvit,

PROSE MACRONS. Here is the same text with macrons written out in prose word order:
Cēra indignē ferēbat lapidēs dūrārī, quod ea vīdit hōs ab igne rapidō sequī. Illa ideō in camīnī flammās sēsē abiicit; putat sē quoque dūram fierī sīc posse. Haec tamen secus cecidēre: igne solūta, liquescit; ea sīc, cōnsūmī coepta, repente perit. Cavē affectāre rem, quam nātūra negāvit; hāc dēstituente, nihil rectē gesseris.
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):
Cera indígne ferébat lápides durári, quod ea vidit hos ab igne rápido sequi. Illa ideo in camíni flammas sese ábiicit; putat se quoque duram fíeri sic posse. Haec tamen secus cecidére: igne solúta, liquéscit; ea sic, consúmi coepta, repénte perit. Cave affectáre rem, quam natúra negávit; hac destituénte, nihil recte gésseris.
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.
Dūrā·rī lapi·dēs in·dignē ·Cēra fe·rēbat,

In flam·mās ide·ō sē·s~ abiicit· illa ca·mīnī,

Haec ceci·dēre ta·men secus,· igne so·lūta li·quescit,

Affec·tāre ca·vē rem,· quam nā·tūra ne·gāvit,

IMAGE. Here is an illustration for the story (image source) showing some wax as it melts:
What follows is an unmarked version of the prose rendering to faciliate word searches: Cera indigne ferebat lapides durari, quod ea vidit hos ab igne rapido sequi. Illa ideo in camini flammas sese abiicit; putat se quoque duram fieri sic posse. Haec tamen secus cecidere: igne soluta, liquescit; ea sic, consumi coepta, repente perit. Cave affectare rem, quam natura negavit; hac destituente, nihil recte gesseris.