I am Johnny Why Not (Run a Marathon) currently training for Grandmas Marathon and it will be my 6th Grandmas(Love Grandmas),14th full marathon. It will be interesting to see how this e-Gel works for me at around 20 miles because that is usually where my legs and time get trashed and I end up doing some walking. Most of the time I have great steady run until around 18 to 20 then the sh– hits the fan. So far I have been training with lots of ten mile runs mostly trail runs. Lots of times I would get a little stiff after these but since these e-Gels I have noticed major energy and no soreness afterwards. I love the Mountain rush flavor. I also take a small metal clip and just take a little shot every mile or so and clip it and put it back in a small bag w zip. I can tell real quick if I am OD ing on it by small burps, then I lay off for a mile or two. I am a 6 foot 5 222 pound 54 year old Clydesdale runner I am thinking 3 packs or 4 should get me through the marathon I will update post Grandmas. I did the trial pack and I LOVE all the flavors.