Where to start??

booooonzo

well you picked the 2 most boring places to start with so it can only get better from here
Keep at it!

emeraldmtb

They're probably not the most exciting trails if you like gravity fed biking and are confident, but (I have never been to Derroura) Ballyhoura is fine for cross-country riding and for building confidence. And if you fancy stepping things up, you can try the tech trails or ask someone to show you some of the Enduro stages

luisspellcast

hey man - i've plenty of time to spare so i'll type an essay for ya - i've recently ruptured my achilles tendon at foxhunt so while i'm at home, might as well stay productive and pass on expertise on the matter ( not my opinion, because you know what they say about people's opinions )

mountain biking is a very broad sport with very distinct categories who caters for various types of people, i.e. their riding styles, body types, personalities, etc.. - unfortunately, it'll only come with a bit of time and practice and experience until you find which path you want to take

renting a bike is your first safe bet, provided you don't rent the cheapest thing money can buy - this is a sport where "bang for buck" doesn't apply most times and if you rent a bike that isn't your size or has bad components, that'll hinder your ride, turning into bad experience, and mtb won't be fun after all - i'm not saying "spend a few hundred everytime you rent a bike," i'm saying "make sure the bike is good so you get a true experience out of it" - free is the most expensive

don't limit yourself to hardtail rentals... see if a trail bike suits, maybe an all-mountain ? i always follow my heart when it comes to chosing what i want to ride - we had an old saying back home when people would ask us which board they should buy first to start surfing and everyone would reply "buy the board you want to surf" - because "learn surfing" and "start surfing" are two very different things; the former could be a disposible activity, the later it's a commitment - only you can say where you really stand - i believe in finding your way and make and educated buy, commit and own your choice

arguably, the second thing you want to do is figure out your gear - some of us have a backlog of a few decades trying and destroying and replacing gear - but what works for me most likely won't work for you - this is where a club comes handy if the people have the knowledge to pass on - keep in mind there's a reason why an aldi helmet and pads will set you back 50euro when you can find the exact some stuff online 10 times that price - the key is to find what works for you somewhere between those two extremes

if you don't have access to a club, or someone that can help you with sizing, stores like chainreactioncycles provide the answer for that question - one way to figure out is buying a set of pads Medium and Large and return the ones that don't fit - sounds daunting but i can guarantee you everyone bought a set of gear that thought it was their size and returned it

when chosing gear, the usual suspects are a) helmet, b) knee pads, c) gloves, d) backpack - first two are self-explanatory, the third is optional but advised, the later will carry the rest of the things you'd find should you chose to go deeper the rabbit hole - down there there's a n) water bottle, n) multi-tool, n) pump and flat repair-kit

pack up your bag and add a couple chocolate cereal bars to it; if on your won, let someone know what you're about to do and when to expect you to text back, bring the phone with you and start pedalling that fire road up --

people love to diss derroura but i believe it's a very good trail - it has a mix of everything and it's close to home - if anything, it's good to go back after months away from it so you can tell how much you've improved - it's like a fitness gauge - there's no money to explore the true potential that the place has but if you don't have any other place to go, it's good enough - i try to distance my real opinion of what any given place is ( or could be ) and chose to think what do i get from going there; what do i learn from being in that place; how can i use the place to improve myself

bike parks are total different beast - give them a go, regardless of your skills as they cater for everyone - however, you gotta know your limits and you gotta know what are you setting yourself for - things get very fast very quickly and that's when things happen - if possible, go with someone experienced or make friends and ask someone on the uplift to show you around - if you're riding behind someone fast you'll rub on some speed, if you're riding in front they might give you some pointers - apart from foxhunt ( where i got a chance to meet the absolute scum of mountain biking during race day ) i have never ever seen a mountain biker that isn't willing to help, specially on bike parks - one last time to keep in mind is that an aldi helmet/pads will only do so much on a place where full-face/body-armour is king - always stay humble, before the trails humble you

and if you don't feel like doing any of that, you can always ride urban - i do it all the time - no friends, phone on silent, headphones and good music and just go practice balacing skills, pedalling on flatland, grab a hot chocolate and watch people jump from blackrock - it's all the little things that make the sport and there's no need to pressure yourself to do things you dont' want to do - and, to answer your question...

.. there is no right or wrong side of the spectrum to pick up the sport - at foxhunt there was a 71 year old fella there - some stuff is just steep and scary but he did it - it always hurts when you fall regardless of your age, except some need to make it to work monday and others don't; or, some will recover in a week and others in a month... again, the key is to know your limits - know when it's time to prevent swelling or manage that internal pain - that comes from you and you alone...

"fitness" in mtb is subjective - my best friend struggles to do a 30kg set of lat, and i do it as a warmup with one hand - however, we've been biking together for ages and i have never ever was able to keep up with him if the words "pedalling" and "climbing" go in the same sentence... that goes to say that body type plays some role into this, so keep in mind sometimes you gotta chose your battles - and if for some reason you find yourself following a group of mtb'ers up the hills, there'll be a fine line between how much fun you're having and how much are you killing yourself just to keep up - they say "it gets easier" but it doesn't, you'll just get better and continue improving

ultimately, figure out what you want to take from this sport and make it your goal - it's a great world - huge world - and i find it most fun when enjoyed with my friends - i do hope you can find your way and do what's best for you - find out what makes you happy when your riding a bike and make it paramount - godspeed !