READ OUT LOUD. Choose which marked text you prefer to practice with - macrons or accent marks - and read the text out loud until you feel comfortable and confident. Then, try reading the unmarked text at the bottom. It should be easy for you after practicing with the marked texts. :-)
MACRONS. Here is the text with macrons:
Leō māgnus dormiēbat in silvā; prope lūdēbant mūrēs, et incautē ūnus nāsum leōnis tetigit. Leō experrectus mūrem corripit. Tum mūs ōrāvit eum: Dā mihi veniam, grātus tibi erō. Leō respondet: Misera bestiola, quid tū mihi prōderis? Sed īgnōscam tibi et dīmittam tē, nam leōnēs sunt generōsī. Effuge. Mūs effugit. - Paulō post leō praedam quaerens inciderat in laqueōs. Fremēbat maximē. Cito mūs, quī fremitum audīverat, accurrit. Acūtīs dentibus laqueōrum nōdōs rōdit et laqueōs solvit. Sīc parvus mūs līberāvit māgnum leōnem.
ACCENT MARKS. Here is the text with ecclesiastical accents, plus some color-coding for the words of three or more syllables (blue: penultimate stress; red: antepenultimate stress):
Leo magnus dormiébat in silva; prope ludébant mures, et incaúte unus nasum leónis tétigit. Leo experréctus murem córripit. Tum mus orávit eum: Da mihi véniam, gratus tibi ero. Leo respóndet: Mísera bestíola, quid tu mihi próderis? Sed ignóscam tibi et dimíttam te, nam leónes sunt generósi. Éffuge. Mus éffugit. - Paulo post leo praedam quaerens incíderat in láqueos. Fremébat máxime. Cito mus, qui frémitum audíverat, accúrrit. Acútis déntibus laqueórum nodos rodit et láqueos solvit. Sic parvus mus liberávit magnum leónem.
UNMARKED TEXT. Here is the unmarked text - after practicing with the marked text that you prefer, you should not have any trouble with the unmarked text:
Leo magnus dormiebat in silva; prope ludebant mures, et incaute unus nasum leonis tetigit. Leo experrectus murem corripit. Tum mus oravit eum: Da mihi veniam, gratus tibi ero. Leo respondet: Misera bestiola, quid tu mihi proderis? Sed ignoscam tibi et dimittam te, nam leones sunt generosi. Effuge. Mus effugit. - Paulo post leo praedam quaerens inciderat in laqueos. Fremebat maxime. Cito mus, qui fremitum audiverat, accurrit. Acutis dentibus laqueorum nodos rodit et laqueos solvit. Sic parvus mus liberavit magnum leonem.
IMAGE. Here is an illustration for the story (image source) by the wonderful illustrator Walter Crane:
