It may not even take much. Do some lunges. Walk up and down some steps (or do box steps). Do some body weight squats. Walk/squat sideways (deep sidesteps) with a band around your knees. Get some form of balance board and spend time focusing on each leg by itself. Stand up and walk around for a minute at work every 30 minutes or hour.
I had gotten way out of whack, and ended up spending some time with a PT. I couldn’t even balance on either foot for 10 seconds. Because 95% of the exercise I did with my legs for 7 years was almost exclusively in one plane on the bike…hunched over, knee goes up, then knee goes down, repeat.