if the weight is 10-15 pounds, i think thats pretty much awesome trade off
and i tell you why - back in good old days, when i was travelling to school and back, each and every day, i took my 12 pounds backpack (laptop, water and stuff) and walked 1/2 mile to train, then 1/2 mile from train to school.. BUT.. when i get bored, i was walking (fast pace) around just to listen music without buses/trains.
anyway, as a 20years old, i did not feel the backpack at all and after I put it down, I felt like a bird.. now im 10 years older... so still young enough to carry heavy weight..
i highly recommend for anyone, to train like this, put 5 pound backpack on, if you are healthy, do not worry, pain and tiredness will not kill you... it will train you.. after weeks or months, you can go as high as 15 pounds and more, and you wont even notice, its on you... eat healthy, move a lot, do not use lift, use stairs instead.. no smoke, little aclohol if you want, no problemo... health and stamina is awesome commodity.. priceless... im always laughing my ass off (but not in bad sense), when my mates (or sadly also wife), whn they have to slow down...
and on top of that, one of my leg is shorter by 1,4 inch. imagine the spine load and so... cant do much about it.. so im a proof, its more will power than anything else..
i get tired, sure i do, but the key is to PICK UP the desired and painless speed/pace and you can go pretty much to the other side of the country without stop... it's like cruising in the car at predefined speed where the MPG is at the best ratio... drink a lot (there were times I drank one full gallon per day (interior work, 77F), but now im trying les, due to kidney or so... but hydratation is important... (spasms protection)
and im only 140pounds heavy/light at 6'
and as lazy as one can be, I never go to gym, i hate it there (boring), but when the activity comes, I try to FOCUS and enjoy the path..
but im not really sure, how much % it adds up, if there will be a crossfire.. maybe its FALSE SECURITY to some... maybe it can take one two shot, and the attacker will run away thinking your hit or so... its interesting, so many outcomes...