How do I say "from this"/"this shows"? Like, "this shows you are lazy" or "from this I can tell you are lazy"
Words I can get are 看出(来)，说明，表明， 表示.  表明 and 表示 can be used in formal circumstances.  

For example, 

this shows you are lazy: 这说明/表明你很懒. 

from this I can tell you are lazy: 从这可以看出你(很)懒.

The way he walks shows that he is self-confident: 他走路的样子说明他很自信.

Your dark tan tells me you like spending time outdoors: 你黝黑的肤色说明/表明你喜欢经常做户外活动。