A lot of it is genetics and cannot be controlled by any pharmaceutical or medical methods so you may have to accept being less hairy than many. I myself have never been exceptionally hairy and what I do grow is rather than and fine. Even my pubes (if I take a break from grooming for long enough lol) are not that thick or coarse! But in addition to that I have inherited alopecia (male pattern baldness) but not just not the usual kind...on me it extends to all parts of my body to a degree. Ironic since many men complain that as they go bald hair grows everywhere elsewhere BUT their head. As I got older...into my 20s and later...what arm and leg hair I had started to thin out. I never had much chest hair or any back hair. I can still grow a good goatee but on the sides of my face I cannot grow a decent beard. Even my pits and pubes thinned out and grow a bit patchy. My hormones are in the normal range though I guess I produce a bit of excess DHT. And autoimmune disorders run in my family and I have always had sensitive skin with the odd flare up of rosacea, dermatitis, etc. which may be related to being folically challenged.
It didn't take much research into hair restoration to decide I wouldn't bother given the expense and side effects, so I took the "Bruce Willis approach" and embraced baldness, shaving off what grows on the back and sides to match the chrome done on top...and eventually doing the same with my pits and pubes since they were longish but thin and scraggly and smooth feels so good lol.
I realize that is exactly opposite of what you're hoping for so here is a bit of what I observed from my research...
One indicator of it being genetic is if you are naturally smooth but other secondary sex development is normal. For example if your cock and balls are big (or at least average), your voice has changed, you have more muscle mass than you did as a teen and do on. If you are concerned beyond just hair growth get your hormone levels and maybe thyroid checked. Hormone replacement therapy will correct most if not all these symptoms including affecting hair growth. Be aware that aggressive or incorrect treatment can make your balls shrink. I'd rather be smooth lol. If your hormones are all good sorry man it's just genetics.
Beyond that make sure you get lots of rest and stay hydrated and eat a clean protein rich diet. You may also try certain supplements like biotin. There are some oils you can massage into your skin regularly that will help strengthen hair and keep it from falling out so it will stay thicker but it won't activate new follicles. Even without any special oils getting frequent massages will help promote good circulation and this healthier hair growth.
Finally, you should be aware that medications for hair growth work on your whole body not just your head. You could use minoxodil/rogaine on your chest, arms, legs etc. But be aware that if you didn't have at least peach fuzz to begin with it won't do much, and it WILL cause itching and redness where applied at least to start with. The drug propecia affects all hair growth too, but again if you never had hair of any kind it won't have dramatic results, and it can lower libido and make you shoot smaller loads.
I personally would recommend embracing who you are without trying to go against it, unless it goes beyond cosmetic issues. The lumberjack trend is a fad that comes and goes...the smooth look WILL be on trends again some day, just like the scruffy rugged look with beard that is in now was what was sexy in the 1970s before we got all preppy and clean cut for a couple decades.
Hope this helps!
