I'm a huge fan of PRESTO, the GTA (and Ottawa's) reloadable transit smart card that lets you pay for transportation across the TTC, MiWay, HSR, YRT, OC Transpo and more. The card lets me save quite a bit of money when riding transit, especially since on my card I'm set up as a post-secondary student.
Though I'm not forced to use GO Transit to visit my family — there's a Via Rail station in my hometown with trains passing through multiple times per day — it's more than half the cost to use the GO, which I receive a 18% discount because of my status as a student.
On both the TTC and MiWay, I'm charged a fare of $3, which is down from the $3.25 the TTC charges and the $3.50 that MiWay cost to ride. Until now, I had always thought that I was paying the lowest fare possible on the TTC — however, my friend pointed out to me that since I'm only 19-years-old, I don't have to pay the adult fare.
Someone aged between 13-19 can pay for the student fare and students aged 16 or over need to carry identification with them. I had always been under the assumption that this meant a high school ID card, but it turns out it includes government-issued ID like a driver's license or a photo card.
Don't bother asking GO Transit ticket agents or customer service to switch you to the student concession, however. You'll need a valid student ID for that.
For people who are willing to carry change around with them, they're able to pay $2.10 for the bus or subway without breaking any official policies or rules.
Though carrying change can be a hassle, it could end up saving you a bunch of money in the long-run. Students who have to take transit to school three times a week could save more than $70 per semester by paying with cash.
(The $70 savings per semester assumes the student travels only from home to school, three times per week round-trip for a 13-week semester; paying the $2.10 cash student fare instead of the $3 adult PRESTO fare results in savings of $0.90 per trip, times six trips per week and 13 weeks, totalling $70.2).