So I have this bad habit.. Any advice?

Whenever I play any mid or ADC, I have this bad habit with cs.

I start the game last-hitting almost perfectly. Missing maybe 1 or 2 per wave tops. But as the game goes on, as the laning phase goes on, I start to fall into bad habits of continual hitting. I get impatient, so I figure "Why not hit the minion a few times, then last hit".. and it turns into not stopping my autos at all.

I know it's a bad habit, and I try to check it, but I don't know how to keep my patience and just farm. I'm not talking about when I'm going to trade, or when I'm pushing towers. I'm talking about when both sides are just sitting there farming. I end up pushing because I can't just let it be.