Vericose prevention ?

I’m noticing some veins trying to crop up. More than w my previous 2 Singleton pregnancies. I’m only 19 weeks. I think I’m doing pretty well (meaning reasonable) w weight gain so far. I’m very active. What makes vericose veins better/worse? Lifting? Sitting? Activity? I realize twins cause more strain but I have at least another 18 weeks to survive 😬😆😂