It's hard to walk around, how do I get more?

There are a lot of ways on how you can get extra Action Points (AP); by clicking Free Credits link to vote on, consuming Spicy Pickles, loading a tool called "AP Boots" that can be found on specific scenes, but for increasing Max AP, you will have to keep logging in everyday, or to go to MD shop and buy an item called "Kinetic Memory." 

Alternatively, you can also find it in the Wish Shop if you have a Wish Point and you feel like this is worth spending it on.

There is no max AP. You have personal max (that also grows) that max can also be overrun temporary (regeneration timer) into infinite numbers.