Answer:
You can work at it by stretching it.
A foreskin is healthy; most guys in the world have it. The USA is the only advanced nation where it's removed a lot, and even so, rates have fallen to as low as about 20% in some states). For example, here are the negative side effects of circumcision:
Circumcision = loss of sensitivity according to new study
http://www.foxnews.com/story/0,2933,2855...
http://www.circumstitions.com/sexuality.
Higher erectile dysfunction rates after circumcision:
http://www.ncbi.nlm.nih.gov/entrez/query...
When women didn't know what penis they were dealing with (circumcised or uncircumcised) 9 out of 10 preferred uncircumcised (study).
http://www.healthcentral.com/drdean/408/...
Foreskin anatomy and function (keeps the glans soft and protects it, etc).
http://www.cirp.org/pages/anat/...
Circumcision is extremely painful.
http://www.cirp.org/library/procedure/pl...
The USA is the last advanced nation doing it, but rates have fallen down from over 90% in the 1960s to as low as 21% here in California currently. From CNN:
http://www.cnn.com/2007/health/06/18/cir...
http://www.cirp.org/library/statistics/u...
Circumcision was actually promoted in the USA at first to stop masturbation (in hopes of it being tight enough to require lubes and not have skin to slide since the foreskin is already moist)
http://english.pravda.ru/science/health/...
USA = highest HIV rates in advanced nations (and highest circumcision rates). CIA statistics:
https://www.cia.gov/cia/publications/fac...
And one study already trashed the claims of the study that said that circumcision reduces HIV.
http://www.plosone.org/article/fetcharti...
Worldwide circumcision rates:
http://www.circumstitions.com/maps.html...
And discussion of common circumcision benefit myths and discussion of all the risks that can develop over time and negative side effects (buried penis, meatal stenosis, etc):
http://forums.govteen.com/showpost.php?p...
As for fixing your problem, some may say that circumcision will fix it, but circumcision's risks include reduction in sensitivity and pleasure, and making masturbation more difficult according to studies (including a few new ones from a few months ago). Oddly enough that's how it was promoted in the USA since masturbation was bad, haha. There's a reason why the USA is the last remaining advanced nation still doing it, and even so, it's getting a lot less popular (it's now as low as 14% in some states). Save that as a last resort, as you're doing. That's only one of the few risks, there's more listed here, in addition to the studies and statistics: