I had a full time 9 to 5 day job, plus some overtime, and I held down a 2nd job working 8pm to 2am. That got me enough money to afford one flying lesson per week, plus set aside some money for a more intensive training rate over the final 30 hours of the course. I did that for 2 years until I got my commercial licence. Then I got my first flying job 2 years after that. Now I've got 6000 hours and earn $100k+ for 6 months work and 6 months holiday per year.
My advice is don't do it unless you can afford it. If you can't afford it work harder to earn more money so you can afford it. Whatever you do, don't borrow the money to pay for flying lessons.