I wish I liked exercise - I never have! 
I too am an analyser. I've always bounced back quickly from exams or periods of intense work though. I find thinking hard does make me tired but to be fair, it is usually combined with burning the candle at both ends so it's hard to know how much to attribute to that! If I am thinking hard for a normal day's hours at work I don't even notice it. At the end of my PhD write-up I was working up to 20 hours a day (and have had periods of those insane hours of analysis through work too, most recently for 6 weeks or so 2 years ago when I had to write a strategy to a ridiculous deadline). I felt pretty rough then. But even after a couple of months of that intensity I can usually bounce back with a week or two's rest afterwards. I think I'm just lucky to be able to switch off once a deadline is past and find it refreshing to think about other things. I can also function okay on very little sleep (even if I don't enjoy it much). I also quite like creative pursuits (cooking, knitting /sewing) and I think they really help me to unwind - they can be quite meditative, so a good background to processing my thoughts, and they can also 'quieten' my mind when it's not shutting down so well. Repetitive movements, hands occupied, seeing something gradually take shape... I really recommend it for those whose minds don't switch off well.
Good day today - only spends were parking for £3. DS has been lovely, bar the odd moment when I took the iPad away . He even came to cuddle me in bed this morning, not something he normally does though I am trying to train him by being effusive in my joy. There's no nicer way to wake up!
I am having this nice thing for dinner - cheap and yummy:
I do tweak it though - no carrots but a couple of chopped peppers (not as frugal but lovely with the beans) and I don't always put spuds in, sometimes I serve it with baked potato. Would recommend it, and defo worth buying the picante pimenton as it is delish.
Also potentially good, an old colleague contacted me today to see whether I am free to do some freelance project work for him. I wasn't intending to do any during this year with DS but being pregnant has changed that a bit as I will need to be off for longer. And I won't qualify for maternity allowance unless i do another 3 weeks' work before the baby comes (because of when I left my job, just short of the qualifying number of weeks' work required). So a short bit of work is quite attractive but I am not sure I will be able to do it... I have 2 days per week where DS is in nursery but I have various maternity appointments (which I have arranged so that I don't have to drag him along) and am also about to embark on the rather onerous process of agreeing his education and healthcare plan which will involve meetings on those days. Hmmm. I am meeting the ex colleague on Tuesday to explore the options anyway. Will see what they want and how flexible they could be about when I work - if I can work from home a bit I can work around appointments and just catch up in the evening. We'll see.