I like to use the I Am, We Are method. Anything I ask of myself, I ask for the world. Its kinda a take on the golden rule. So for example...

I am the designer of an amazing journey/We are the designers of a collective amazing journey.

I am strong and healthy physically, emotionally, mentally and spiritually/We are strong and holistically healthy.

I am strong enough to face my demons, accept them and integrate them into a better future/We are able to face our evils, accept them and redesign them for a better future

Really any way you want to go about mantras can work. Just say everything as a truth because if you can think it and wish it for yourself, there is a part of you that is already there. The same is true on a collective level.