If you have a good level of fitness, you should be OK.
And if you don't mind being dicked about by someone ten years your junior. And living in a room full of eighteen year old kids. And being told when to eat, smoke, shit, sleep etc. And after recruit training, being a thirty five year old Private, your peers will be Sergeants and above.
But if you are sure, do it and good luck to you.
I joined at nineteen and having trained reserve recruits who were in their thirties and forties, I just find this desire to join later in life, absolutely baffling.