I am a financial analyst; I design quantitative market models. I have traded my own account in the financial markets for many years and continue to do so. Sometimes for better, sometimes for worse. All trading goes through good and bad patches. It is something you learn to live with. The goal should be to contain risk within levels you can tolerate, both financially and emotionally.
Traditional discretionary fund management is outdated and discredited. Simple rule-based investing is likely to provide (over the long term) better risk-adjusted returns than conventional approaches.
Some of my models are very simple (in principal). Some are slightly more elaborate and use a sophisticated but slim set of rules and money management techniques. My guiding principal is robustness.