How do I get endurance charges for boss fights?

Hi,
I'm new to poe and I followed a guide to build a Reave / Blade Flurry Juggernaut with 2x Ahn's Might. A big part of survivability comes from Endurance charges if I understand it correctly.
If I have full endurance charges I have no problems surviving at T14 maps (my highest so far) but when my charges are at zero, especially before boss fights, I can be one shot before I manage to generate any.
Is there a way to generate at least a few endurance charges before getting close to enemies?
Thanks!

you can swap your belt with gluttony unique leather belt and use couple leap slam thats easy max endurance charges
/ swap your belt , use your movement skill , get endurance charges , swap back your real belt

also you can swap your boots with Ralakesh's Impatience unique boots and just wait this way you can get other charges too
/ wait till you get charges , swap back your real boots without moving

That belt option works well, thank you!
If only there was a weapon for the secondary slot that did the same :)