Days of prayer, and formerly also of fasting, instituted by the Church to appease God’s anger at man’s transgressions, to ask protection in calamities, and to obtain a good and bountiful harvest…

The Rogation Days are the 25th of April, called Major, and the three days before the feast of the Ascension, called Minor.

The order to be observed in the procession of the Major and Minor Rogation is given in the Roman Ritual, title X, ch. iv. After the antiphon “Exurge Domine”, the Litany of the Saints is chanted and each verse and response is said twice. After the verse “Sancta Maria” the procession begins to move. If necessary, the litany may be repeated, or some of the Penitential or Gradual Psalms added.

Catholic encyclopedia on “Rogation Days”: https://www.newadvent.org/cathen/13110b.htm

Based on this, I’ve sometimes thought people might observe the days at times by fasting, and by praying a Litany of the Saints and / or the Penitential Psalms.

Litany of the Saints: https://www.dailycatholic.org/litanyst.htm

About the Prayer: https://www.newadvent.org/cathen/09291a.htm

Penitential Psalms: https://traditionalcatholicprayers.com/2020/09/26/the-seven-penitential-psalms/