"Practice makes perfect" is a tricky aphorism. We all know that the act of practicing is essential to improvement, but the questions of what, how, and how much to practice can often feel overwhelming or the answers are just shots in the dark. To improve, we need to work on intentional practice - yes, practicing takes practice. Intentional practice doesn't necessarily mean setting an alarm to remind yourself to sing everyday - although that's not a bad idea. Intentional practice is mindful practice. It is disciplined. These skills aren't easy with distractions, impatience, and the always capricious ignitor, Motivation.
A teacher can help you diagnose faults or set goals and help put in place specific exercises to address issues. But it is your job as the wanting-to-improve singer to implement the new habits (or eliminate the bad). New skills or approaches take consistent revisiting to form muscle memory and reflexive anticipation so that they don't distract from the whole multitasking system of singing. It takes practice to override a day's worth of normal-life habits and turn your body into an instrument.
All of this is to say: try to practice every day, even if only for two minutes, and observe your approach. You will get better at it (practice) and you might even start to enjoy the process of improving your practice. Even if you don't make a sound, remind your body what it needs to do to become an instrument. Exercise the part of your brain that focuses on detail and sensation. Reinforce already good habits with mindful maintenance - don't neglect what's already working. Exercise your enjoyment of singing. Sometimes this takes intentional effort as well.