1. A method for acquiring magnetic resonance data from a breathing subject, comprising: using a processor to subdivide a respiratory position in a respiratory cycle of a breathing subject into a plurality of respiratory position sub-ranges, and to assign each of said respiratory position sub-ranges to a predetermined cluster in a plurality of clusters, each cluster encompasses a predetermined respiratory sub-range of said respiratory position sub-ranges; operating a magnetic resonance apparatus to acquire a measurement data set, comprising magnetic resonance data from the breathing subject, in a plurality of shots, with the magnetic resonance data of each shot filling a predetermined number of lines in k-space that is less than an entirety of all lines in k-space, and each shot exhibiting a three-dimensional k-space trajectory in k-space, with respectively different shots filling respectively different lines in k-space such that each shot fills a predetermined k-space region; using said processor to assign a respective shot index to each of said shots that designates a sensitivity of the respective shot to movement by the subject, and assigning said shot indices to the respective shots with adjacent shot indices being assigned to respective shots, among said plurality of shots, that exhibit an incrementally different sensitivity to said movement with a shot exhibiting a highest sensitivity to said movement receiving a shot index in a middle of a total index range; using said processor to assign a set of shot indices to each of said clusters, said set encompassing a range of adjacent shot indices that is cyclically extended at the index range boundaries such that the highest shot index is adjacent to the lowest shot index and vice versa, said set of shot indices of all clusters initially being empty; using said processor to assign a start index to each of said clusters, said start index corresponding either to a shot with a high sensitivity to said movement or to a shot with a low sensitivity to said movement, with start positions with high and low sensitivity to said movement alternating between bordering clusters that encompass adjacent respiratory position sub-ranges; operating said magnetic resonance apparatus to acquire the respective shots by (A) acquiring respiration data from the subject that indicate a current respiratory position of the subject at a time when the respiration data are acquired, (B) using said processor to select a specific cluster, in said plurality of clusters, that has the respiratory sub-range assigned thereto that contains the current respiratory position of the subject, (C) using said processor to select the start index of said specific cluster for a shot to be acquired, if the shot index set of said specific cluster is empty or, if the shot index set of the specific cluster is not empty, selecting a shot to be acquired that has a shot index that does not belong to the shot index set of said specific cluster yet and that has a shot index that borders a shot index that has already been assigned to the shot index set of said specific cluster, and (D) acquiring said shot to be acquired and assigning the shot index of said shot to the shot index set of the specific cluster; repeating (A), (B), (C) and (D) until the shot index sets of at least two bordering clusters, that encompass adjacent respiratory position sub-ranges of the subject, collectively encompass the shot indices of said shots in said measurement data set; using said processor to determine said respiratory cycle of the subject, said respiratory cycle comprising at least two respiratory cycle phases; using said processor to determine, from said shot index sets of said at least two bordering clusters that encompass adjacent respiratory position sub-ranges of the subject, the respiratory cycle phase of the subject during which said magnetic resonance data were acquired; and reconstructing an MR image from magnetic resonance data of said shots assigned to said at least two bordering clusters by executing an image reconstruction algorithm that reconstructs said MR image dependent on the determined respiratory cycle phase.