It can be an act of charity if you make it an intercessory Holy Hour. For example, if you want to make pro-life issues your theme during a particular Holy Hour, you can spend time interceding for abortion doctors, abortion clinic workers, pro-abortion advocates, legislators, judges, etc. Then you might say a rosary for women currently faced with an unexpected pregnancy and/or recite the Divine Mercy chaplet for women in Purgatory who are making reparation for abortion. You can ask the Lord to strengthen those on the frontlines of the pro-life fight. Then at your next Holy Hour you can have a new target for your intercession, such as priests, or the salvation of the dying, or atheists, or abused children, or someone who’s been a thorn in your side, etc.