All I can say is that I used to work in a so called 9-5 environment. Ended up with the usual weekends off and 20 days holiday a year.
Although I work for a private company, when I did work for NATS as an ATSA and then subsequently became an ATCO , I enjoy lots of free time (Far more than all my non ATC mates), and love going into work.
There aren't many of my friends that can say that.
As for the stress levels. I have just bought a house. Theres not much more stress than that, that I have encountered in the job.
If you aren't up to it you will soon find that out during the training (Although quite abit different from the live traffic)
I say go for it . I started in my late twenties and wish I had started at your age.
Good luck in whatever you decide to do.