Something to consider is that in general, there is no such thing as 'too much rest' to anyone. There are monks who sit and follow their breathing the whole day through, thinking as little as possible, and breaking only to eat, sleep, or use the bathroom— and some will follow this routine for months and months.

So in that way, it doesn't really matter how "little" you do, as long as you're not getting any more brain injuries.

Anywho, for me, the most important thing is to stay out of bed and to stay active for the whole day, even if "active" just means doodling or going for a slow walk for an hour, doing dishes, and so on. I would call those activities "restful", in that they don't make me feel anxious, dizzy, physically, or mentally overwhelmed. Of course, to someone in the first weeks and months following a TBI, these things might not be considered restful, and would probably cause a potentiation of symptoms. So I second Deuce's idea of "do what you feel is right," because likewise, what's rest to me may be stress to you, and vice versa.

I agree, if your body tells you rest, then rest. You can't push through a concussion. I know another young student who had recovered then relapsed with post concussion after she started her first job where there were very bright, florescent lights in the office.
I keep a daily journal to see how I am doing and what things are affecting me. Some days i do light activity and other days I do nothing but rest. I take note of hours of sleep, if I exercised, took vitamins, what activities I engaged in or if I did nothing all day, if I meditated etc. Then I note what symptoms I experienced or how I felt that day. It has aided me in seeing what's working and what's not and I can also relay this to my doctor when I see her.
Just a thought? :-)

I second the idea of keeping a daily log. I wish I had done that since the beginning of my concussion, but I started to keep a video log on my computer every day for the past two months or so.

Unfortunately for me it hasn't helped in detecting any actual patterns, as my symptoms seem to be randomly better or worse on any given day regardless of what I've been doing. Sometimes there isn't any clear patterns, but regardless it's nice that if you're experiencing something that was similar to a previous day, you can check back on your log and see if there was any similarities to those days. Just avoid doing it if you're going to constantly obsess over it though, as I feel that might hurt more than help.

Still, it could be helpful to see if you're doing better on days where you're resting a lot vs. pushing through it.