We also have his testimony as to the nature of his work, and his further testimony that he did not think of compensation for any work-relationship to his heart disease until several years after leaving work. "`We superimpose on this matrix of evidence the Board's right to draw reasonable inferences from the proofs before us (Forner v American Box Board Co, * * * [ 319 Mich. 165; 29 N.W.2d 273 (1947)]). "`We are aware of the Court's directives not to impose any improper legal tests as to the necessity of a specific injury or certain degree of stress before a finding of work injury can be made (Sheppard v Michigan National Bank, 348 Mich. 577 [ 83 N.W.2d 614 (1957)]; and Zaremba v Chrysler Corp, 377 Mich. 226 [ 139 N.W.2d 745 (1966)]).