vacilar

vacilar
bah-see-lahr'
to waiver, to vacillate; to hesitate
Examples
1. Me cuesta no vacilar en mi resolución de comer mejor.
It's hard for me not to waiver in my resolution to eat better.
 
2. No debes vacilar cuando se te presenta una oportunidad así.
You shouldn't hesitate when an opportunity like this presents itself.