Take for instance, a man who ponders much in one incarnation — who thinks and ponders a great deal. In his next incarnation he will be a thin, delicately made man. A man who ponders little in one earthly life, but lives a life more concerned with grasping the outer world, tends, in the next life, to accumulate a good deal of fat. This, too, has a significance for the future. Spiritual “slimming cures” cannot well be managed in one earthly life; for this one must resort to physical cures — if indeed they are of any help! But for the next earthly life it is certainly possible to undergo a “slimming cure” if one ponders and thinks a great deal, especially if one thinks about something that calls for effort, of the kind I described yesterday. It need not be meditated, but simply pondered about a great deal, with the willingness to make many inner decisions.
There is an actual connection of this kind between the spiritual and moral way in which a man lives during one earthly life, and his physical constitution in the next earthly life. This cannot be emphasised sufficiently.
Source: Rudolf Steiner – GA 236 – KARMIC RELATIONSHIPS II – Lecture VIII – Dornach, 10 May 1924
Translated by George Adams with revisions by M. Cotterell, C. Davy and D. S. Osmond