Rudy's OBTF

Total exercise duration

… is the sum of all exercise durations

\begin{equation*}
  \frac{\sum_{d \in D} f(d)}{60 \cdot 60}
  \approx
  \boxed{MY-TOTAL-EXERCISE-HOURS} \, \text{hours},
\end{equation*}

\begin{equation*} \frac{\sum_{d \in D} f(d)}{60 \cdot 60} \approx \boxed{557.45} \, \text{hours}, \end{equation*}

computed by

(defun my-total-exercise-hours ()
  "Return the sum of all exercise durations in hours."
  (format "%0.2f"
          (/ (let ((total-duration 0))
               (maphash (lambda (day duration)
                          (setq total-duration
                                (+ total-duration duration)))
                        (my-exercise-log))
               total-duration)
             (* 60 60))))