Task

it’s not brain surgery

Meaning: to indicate that a specific task is simple and easy to undertake 

Example: Learning to ride a bike is simple, it's not brain surgery. Read on

a tall order

Meaning: a challenging task or difficult requirement

Example: Telling a player to score six goals in one game is a tall order. Read on

in at the deep end

Meaning: to start a new job or activity without being prepared for it

Example: thrown in at the deep end Read on

no picnic

Meaning: used to express that an activity or action is not fun

Example: I love having little kids around but cleaning up after them is no picnic. Read on

Herculean task

Meaning: a task requiring huge amounts of physical strength

Example: It will be a Herculean task to get through to the quarter-finals, but this untested team is up for the challenge. Read on