Comment by coldpie

Don't know about Switzerland, but most US brokers offer some kind of "target retirement date" fund, which automatically shifts from higher-risk assets to lower-risk as you approach retirement. VFIFX is one from Vanguard, for example. Pick one you like (just ask a coworker what they use, if you pick a big-name brokerage it really doesn't matter which one), shove your extra cash into it regularly, and forget about it. Then cross your fingers the market isn't actively crashing when you plan to retire (this is unlikely, but it does happen a couple times per century).

If you start to get into truly high wealth amounts (USD$500K+) you might consider hiring a wealth advisor, who can probably do better even after accounting for their fees.