should i go back to school ?

ok i was thinking bout going back to school to become a cardiovascular tech but the only problem is they recommend not working because the program is very tedious. i work full time so im a little afraid of letting my job go where i get my pay check every week but i know it will better my future.. so im prolly gonna get a small part time job to bring in some extra money.. the only thing thats stopping me from going back to school and quitting my job is im 28 years old and i feel like its to late to go back to school and not have a full time job.