Healthy feet make for happy, healthy people.
The most common foot complaints I encounter in walkers and people who enjoy regular exercise are athletes foot, hard skin and blisters. With some simple precautions, these can be reduced to a minimum.
Ensure your footwear is a comfortable fit and in good repair. Footwear which is too big may result in you slipping and causing damage to your ankle. Footwear which is too tight will result in rubbing, causing blisters and corns. Footwear in poor repair, or past it's 'use-by-date' may lack grip on the sole, loss of shock-absorbency, and may not provide sufficient ankle support.
Hard skin or 'callus' is built up through excessive pressure being exerted on an area of the foot. This could be around the borders of the heels, due to being 'heavy footed', or on the side of your 5th toe joint due to your foot not striking the ground at the correct angle.
Check Your Shoes
In most cases, a good foot file will help reduce the hard skin and apply a moisturiser (emollients with 10% urea usually work best).
To reduce the risk of build up again, check the cushioning within your walking boots or sports shoes, and if need by, replace the insoles with a more shock-absorbing insole (gel or foam based should be fine). This should allow the excessive pressure to be absorbed by the shoe, and distributed more evenly across the sole of your foot. If your hard skin continues to develop, it may be worth visiting a podiatrist for a biomechanical assessment. Orthotics can be made to aid foot functionality, or to deflect pressure away from areas.
The Dreaded Blister
Blisters are caused by friction or rubbing on the skin. The blister occurs when the top layer of the skin becomes separated from the layer beneath, and the 'blister' becomes filled fluid.
Prevention is better than cure. There are various methods, but the most common is to moisurise the foot with vasaline and apply an ankle stocking to aid retention of the coating. Other methods are to wear 2 thin pairs of socks, which will absorb the friction, removing it away from the skin.
Treatment of blisters - NHS recommends NOT bursting them. This is a rule you should try to adhere to, especially if you are diabetic. Otherwise, if it is painful, and likely to burst during a walk or other activity, then taking preemptive action may prevent further trauma to an open wound. Most guides suggest piercing them with a sterilised needle (boiling water / alcohol swab - NOT naked flame). Then gently squeeze from the sides to remove all fluid. Firmly apply an Elastoplast / sterile dressing to the remaining skin to help the repair, and prevent infection.