So your hairline is just receding a little? Honestly, I think your hair looks pretty good. I'm 30 and I have a similar hairline, and if that was my only issue, I'd be stoked. I've also got some thinning going on in the crown area, so while it still looks OK now, I know that I'll probably need to shave it all off by the time I hit 35 or so. I noticed my hair starting to thin when I was 19/20 - it kept going until around 23/24, after which it stayed pretty much the same until last year, and now I'm going through another round of thinning.
As others have said, hairline maturation is just a part of getting older - you don't keep the hairline you have when you're a teenager and the older you guys you see who have one clearly just got plugs. And hey, that's a legitimate option if you really want to keep your hair - look at all of those famous people who were balding in their early to late 30s who now sport thick, full heads of hair (Joel McHale, Steve Carrell, Jaime Foxx, etc). But that shit is expensive, so if it doesn't *really* matter to you, just accept it as it is, get your hair cut often (a solid barber can do a LOT to make thinning hair look good), and when you pass that point where short hair isn't cutting it, shave it down.
Luckily for me, I met my fiancée when I still had total coverage (i.e. I could still sport semi-long hair) and she's long-since accepted that I likely won't make it to 40 before submitting to the baldie lifestyle.