British territorial expansion in India throughout the 19th century created an institutional environment that, on paper, guaranteed property rights among the colonisers, encouraged free trade, and created a single currency with fixed exchange rates, standardised weights and measures and capital markets within the company-held territories. It also established a system of railways and telegraphs, a civil service that aimed to be free from political interference, a common-law and an adversarial legal system.[108] This coincided with major changes in the world economy – industrialisation, and significant growth in production and trade. However, at the end of colonial rule, India inherited an economy that was one of the poorest in the developing world,[109] with industrial development stalled, agriculture unable to feed a rapidly growing population, a largely illiterate and unskilled labour force, and extremely inadequate infrastructure.[110]
I would throw in some caution here: if your spouse works at the same company, or in the same industry as you, you are not diversified, and should something happen, you could be in a world of hurt.  Companies do go out of business, companies do lay employees off.  There is nothing wrong with working together, but realize that you are not diversified and you should be trying to maximize other income streams as a result.
1) If your property is not under rent control, you have the ability to raise rent to market prices with proper warning. In SF, I have to give tenants a one month warning for up to a 10% increase and a two month warning for up to 60%. Rent control limits to an inflation index, usually around 2% a year, which is why initial pricing and tenant turnover is important for better profitability.
I prefer assets that make me a high return for the lowest amount of work possible (semi-passive involvement). And assets that pay me in several unique ways. Cash flow is only one way RE makes money for me. I also get principal reductions, appreciation, tax advantages (depreciation), and I control the rental increases on a yearly basis. Plus a majority of the capital is provided by the secondary market on 30 year fixed low interest rate debt.
The Indian economy was large and prosperous under the Mughal Empire, up until the 18th century.[71] Sean Harkin estimates China and India may have accounted for 60 to 70 percent of world GDP in the 17th century. The Mughal economy functioned on an elaborate system of coined currency, land revenue and trade. Gold, silver and copper coins were issued by the royal mints which functioned on the basis of free coinage.[72] The political stability and uniform revenue policy resulting from a centralised administration under the Mughals, coupled with a well-developed internal trade network, ensured that India–before the arrival of the British–was to a large extent economically unified, despite having a traditional agrarian economy characterised by a predominance of subsistence agriculture,[73] with 64% of the workforce in the primary sector (including agriculture), but with 36% of the workforce also in the secondary and tertiary sectors,[74] higher than in Europe, where 65–90% of its workforce were in agriculture in 1700 and 65–75% were in agriculture in 1750.[75] Agricultural production increased under Mughal agrarian reforms,[71] with Indian agriculture being advanced compared to Europe at the time, such as the widespread use of the seed drill among Indian peasants before its adoption in European agriculture,[76] and higher per-capita agricultural output and standards of consumption.[77]
Investing in a business: Another good way to generate passive income is to invest in a business --even a small one -- in return for a percentage of the profits - just like Shark Tank, only smaller. Lending $10,000 to a local business that, for example, is working on a mobile app for Apple phones could lead to a passive income-generated share of the profits when that mobile app starts selling like hot cakes.
The reverse can also be expected unless the rents rise too.  This rental increase might occur if we imagine interest rates are rising because the economic environment is improving.  At present, it is widely expected that rates will rise ever so slowly over many years.  Indeed the US has been looking for the courage to do this over recent months and they may start rising there soon.