I Am On the Computer Too Often

This is something that I need to address at home. I live with my parents, my sister and her kid, and yet all they see me o most of the time is look through youtube an random shit on the internet. They all feel there isn't a moment where I'm not away from my computer an there right. I should be doing more around the house to help.
Don't get me wrong I help with everything they ask for, but that's not after some reluctance on my part, I feel like I should be up for whatever considering I have a bit of time on my hands when I get home from work. But I start to feel tired whenever I get home, mostly due to lack of movement after work. We live on a farm you see, and only being 27, I should have more than enough energy to get up and voluntarily help out, yet I feel like when I get home all my energy is gone and all I want to do is browse the net.
I want to stop feeling the need to get on my computer and get into a mindset were I have nothing but time for my family after work, because they think I have no interest in what's going on around me and only have an interest for whats going on behind a screen.

Basically I want to know if you have ha trouble with this in the past and how have you helped yourself with the know;edge you had?