Don 't worry about things so much .It will make you stressed

it 代替的不是things（事情）
而是 worry about things so much （太担忧那些事情）这种状态,就是“担忧” “担心” 这样的状态,或者心情.用it 代替
will 后面都接动词原形
will/would是助动词,因此后面如果接动词时,必需是动词原形