In your 20s....

• Your backpack consists of mostly bikinis, sarongs, and sundresses, having forgotten that you might be at altitude at times and then have to panic-buy warmer clothes in Peru for the Inca Trail.
• Your backpack is so heavy (also full of guide books, as this is the pre-Kindle era) that you can barely put it on yourself.
• Having lived for almost a whole quarter-century you feel worldly and mature, yet still look at people travelling in their 30s and think "wow they are much older, good for them doing this at their age…".
• You can party hard with fellow travellers, for consecutive nights on the trot, without really breaking a sweat.
• You fancy hippy Harry and surfer dude Charlie, and try and impress them with previous travel tales: "There was this one time, in Brazil, when I got bitten by a piranha…"
• You'd never consider doing a city 'walking tour', sounds way too boring and adult.
• You think nothing of getting on a night bus and not getting a solid 8 hours sleep.
• Anxious to get a kick-ass tan, your absolute highest sunscreen factor is SPF15.
• You get a lot more male attention in your 20s, particularly in Latin America, maybe it was because of the age, more likely because you weren't with your husband.
• Most of your friends at home are doing the sensible thing and settling into the start of their careers, but you are too young and carefree to worry.

In your 30s....

• Your backpack consists of sensible layers, special hiking socks and clever clothing which packs up really small.
• Your backpack is half the size of your backpack in your 20s as you have learnt that you really don't need that much.
• You look at those in their late teens/20s and think "wow they seem so young, yet think they know it all, was I that worldly (ahem) in my 20s?"
• You have the odd night of excess beer/rum/local liquor and its invariably the night before you are due to travel all day the next day which ensures you are sweating rum fumes on a hot bus, swearing at your husband for letting you drink so much when he knows that you will be a grumpy, hungover wreck the next day.
• Harry and Charlie are idiots.
• Before you know it you have been on three walking tours in the last three months, don't you know they are actually very interesting and good way of getting local knowledge etc etc.
• Although taking a night bus saves on accommodation costs, you are concerned that you might be 'a bit tired' the next day.
• Anxious to keep wrinkles at bay, your highest sunscreen factor is SPF 50.
• From Simon: when travelling around Asia you don't get anywhere near the same amount as (female?) attention, maybe because you are in your 30s, probably because you are travelling with your wife.
• Most of your friends at home are doing the sensible thing and having children, and while not so young now, you appreciate how relatively carefree you still are, as it is those that have already had kids that are the most encouraging about your trip. This makes you realise you have done the right thing for now, and that parenthood will hopefully be another adventure waiting to come. But first, pass me another beer please, its too difficult to get out of my hammock to do it myself...