Someone says to you: "you must be doing agile, continuous integration, continuous deployment, automated testing, test driven development, etc. etc. etc. or you're doing it wrong".
For any sufficiently complex application you’re building it's likely that the above things, and more, will be beneficial.
The problem is if you’re not doing any of these things and you feel overwhelmed where do you start?
You start where you're at.
build on each success with subsequent success
I remember watching Ray Mears on TV once and he used the acronym STOP to remember what to do if you get lost or stranded:
If you feel overwhelmed this may me a useful acronym to help you start where you're at.
Accepting where you are now and starting where you're at can help remove negative feelings and the feeling of being overwhelmed and not being "good enough" at your job.
This of course doesn't mean that you should accept unprofessional practices and not try to improve things, it simply means acknowledging without judgement where you are now and then moving forward to improve things for the future.
You can start with the "big rocks", the more important or foundational things such as making sure you're using adequate source control. Maybe then move to implementing a basic continuous integration build. Maybe then start to add some automated tests, etc. etc.
Do things incrementally and build on each success with subsequent success.
To create the change you desire, you may have to invest in you along the way, develop an understanding that discipline equal freedom, and also ask yourself the question “what would easy be like?”.