I've hiked many trails in San Diego but I can honestly say that El Cajon mountain is one of the toughest hikes I've ever done.  We set out on the trail early at about 6:45 and packed with water and energy bars we made it to the summit in two hours and 20 minutes. Gorgeous day, and only started to get warm at the top of the summit.  The descent on this out and back is, in a word, painful!  There’re moments where you have to “chop” (baby steps) your way down the hill to prevent from falling. I feel like my quads were burning MORE going down than they were going up.  This is definitely a must hike in San Diego, and I'm surprised I haven't hiked it until now.  As hard as I thought it was, there were others on the trail that were doing it twice!  WOW!!