The "make mistakes" isn't, "do drugs and get STDs and fuck up your life!", it is "try things that you might not like" or "date two women at once" or any variety of "mistakes" that people are afraid of doing at that age.
Also, life doesn't end at 30, quite the opposite. I love being my age (well over 30!) and am very physically active. But traveling is a hell of a lot easier when young, because you don't have kids and bills and pets and all the other things that are great later in life (well, not the bills, but the things you get for paying those bills), but make floating around difficult.
And there's no way to compare the physicality of someone in their 20s with someone in their 40s. If you think so, you were not physically active in a significant way in one of those two ages brackets. I could play soccer for hours in my 20s, but I had to finally give it up at 45 because it's just too hard on the body.