(inspired in part by the way Beth Harmon plays through games in her mind in the novel/TV series “The Queen's Gambit”)
A little blindfold challenge which provides the opportunity to practice visualizing the board, the moves and the resulting positions all in one's mind. It's quite tough (at least I think it is)—especially as the game progresses, it is quite common for the visualized positions to become increasingly fuzzy and to start forgetting where certain pieces/pawns were placed, etc.—but trying as best as one can to pull through will help tremendously in improving one's calculation skills.
Some helpful resources
- https://odinchess.com/ Includes a number of exercises as well as the possibility to practice playing blindfold against a chess engine by typing the moves in algebraic notation.
- Reading chess books and imagining the moves in one's head (without playing the moves out on the board), just as Beth Harmon did. It is difficult at first, but quite useful in improving visualization skills. I find it of course considerably easier if the book shows a number of diagrams for each game—the best way to start is probably to choose a book that has frequent diagrams every few moves.