Have you tried using WolframAlpha? If you get the pro subscription (~$66 per year - ~$45 a year for students) you gain access to their step by step solutions and unlimited problem generator. I am currently studying a Masters of Biostatistics (which has a heavy calculus section) and found this service invaluable.
Mine went "See if someone has already stated what you want then up-vote them, OP and be done with it"
Wasting time fixing a problem rather then starting a fresh i.e. biology/genetics - rather then just ordering in new primers(oligos), reagents(Taq, nucleotides etc) wasted a few weeks trying to find out which specific component was faulty. All the components are not very expensive while time tends to be - especially for scholarships.
I work at a University as a research assistant in the Biology Department and I am currently studying part-time in a masters of Biostatistics. One of the main reasons (apart from enjoying it) why I began to take statistics seriously was due to a) most of the PhD students lack of knowledge of statistics and b) complete and utter ugh-fieldness in having to do statistics.
I think your reasoning is good (though that just maybe cause it aligns with mine) just don't forget how many companies/corporate jobs there are for data-science now especially when the money seems very good. I have come to the opinion that going into academia via the "traditional" route is flawed and most definitely not for everyone (see shminux's comment) i.e. PhD -> then madly applying for very competitive (depends on field but mostly true?)post-doc positions ->even more competitive faculty job -rinse repeat. Perhaps that's just my hesitance as it seems to be a path of continual narrow specialization with unequally increasing competitiveness.
Could you go into a little more detail by what you mean by recovered from depression and what aspects of CBT assisted the most?
I am under the impression that a lot of those Brain Training games you may find won't work as claimed i.e. those (Luminosity etc) that claim working memory improvement --> intelligence improvement/cognitive improvement.
Here is a relevant meta-analysis of such (haven't been able to get an original copy have just read through this article
Tis a shame cause I watched the same program and got excited but decided to investigate before I paid up for it.
You have also lead to me implementing Secret Weapon by mentioning it here.
EDIT:Having now done this for 6 months I can attest to sticking to it and it very much being helpful for both checking on what I have done that day and planning for future days. Will keep doing it
Thanks for putting it far more eloquently then I my brain had
Fourthing the exercise habit. A good tracker I have found to stay at it and for confidence building is Fit-o-Cracy