I just can never be discipline to continue to jounal ANYTHING. Food, training, etc. In the past I have tried, then I fall out of it and start over again, so my old training logs have big gaps in time.
I have a friend who logs not only distance, how she felt, etc. But weather, temperature and wind. She also uses this to know when to chnage tires and other bike maintence. But she is a "data" geek and loves Excel. I am just not that dedicated.
The only saving grace now is that I have to log all my workouts now that I have a coach. So I do log time and just recently looked and can se how many hours I spent in "training" since May. I can probably get more data out of it, just have to figure out how to run the reports.
Others have great advice. To me it depends on how much detail you want to put in and will do consitently. And method...paper for portability or spreadsheet to have totals and be able to look at it over time.
Good job on starting the walking and expanding your exercise. Seems one sport/discipline is never enough or solves all our health problems/needs.